{
  "paper": {
    "school": "Nan Hua",
    "year": 2022,
    "level": "P4",
    "label": "Semestral Assessment 2",
    "source_prefix": "Nan Hua 2022 P4 Semestral Assessment 2",
    "has_answer_key": true
  },
  "questions": [
    {
      "n": 1,
      "type_id": 1,
      "question": "72 thousands and 3 tens is the same as [?]",
      "answer0": "723",
      "answer1": "7230",
      "answer2": "72 003",
      "answer3": "72 030",
      "correct_answer": 3,
      "skill_id": 105,
      "difficulty_id": 1,
      "explanation": "72 thousands = 72 000 and 3 tens = 30. 72 000 + 30 = 72 030.",
      "hints": ["72 thousands means 72 000.", "3 tens means 30. Add them."],
      "source": "Nan Hua 2022 P4 Semestral Assessment 2 Q1",
      "image_needed": false,
      "image_options": false,
      "image_file": null,
      "notes": ""
    },
    {
      "n": 2,
      "type_id": 1,
      "question": "Which of the following is a factor of both 28 and 60?",
      "answer0": "10",
      "answer1": "8",
      "answer2": "7",
      "answer3": "4",
      "correct_answer": 3,
      "skill_id": 113,
      "difficulty_id": 1,
      "explanation": "Factors of 28: 1,2,4,7,14,28. Factors of 60: 1,2,3,4,5,6,10,12,15,20,30,60. Common factor among options is 4 (4 divides 28 and 60).",
      "hints": ["A factor divides the number exactly with no remainder.", "Test each option: does it divide both 28 and 60?"],
      "source": "Nan Hua 2022 P4 Semestral Assessment 2 Q2",
      "image_needed": false,
      "image_options": false,
      "image_file": null,
      "notes": ""
    },
    {
      "n": 3,
      "type_id": 1,
      "question": "Write 4 7/20 as a decimal.",
      "answer0": "4.72",
      "answer1": "4.7",
      "answer2": "4.35",
      "answer3": "4.035",
      "correct_answer": 2,
      "skill_id": 127,
      "difficulty_id": 2,
      "explanation": "7/20 = 35/100 = 0.35. So 4 7/20 = 4 + 0.35 = 4.35.",
      "hints": ["Make the denominator 100: 7/20 = 35/100.", "35/100 = 0.35, then add the whole number 4."],
      "source": "Nan Hua 2022 P4 Semestral Assessment 2 Q3",
      "image_needed": false,
      "image_options": false,
      "image_file": null,
      "notes": ""
    },
    {
      "n": 4,
      "type_id": 1,
      "question": "ABCD is a square. Find ∠x.",
      "answer0": "65°",
      "answer1": "60°",
      "answer2": "55°",
      "answer3": "25°",
      "correct_answer": 3,
      "skill_id": 197,
      "difficulty_id": 3,
      "explanation": "Angle BCD of the square = 90°. The marked angles at C are 35°, 30° and x. 90° − 35° − 30° = 25°. So ∠x = 25°.",
      "hints": ["The interior angle of a square is 90°.", "The three angles at corner C (35°, 30° and x) add up to 90°."],
      "source": "Nan Hua 2022 P4 Semestral Assessment 2 Q4",
      "image_needed": true,
      "image_options": false,
      "image_file": "q4.png",
      "image_page": 3,
      "image_bbox": [0.6, 0.66, 0.9, 0.86],
      "image_loc": "lower-right of page, square ABCD with diagonals and angles 35°, 30°, x at corner C",
      "notes": ""
    },
    {
      "n": 5,
      "type_id": 1,
      "question": "9 5/8 = [?]/8\nWhat is the missing number in the box?",
      "answer0": "45",
      "answer1": "67",
      "answer2": "72",
      "answer3": "77",
      "correct_answer": 3,
      "skill_id": 119,
      "difficulty_id": 2,
      "explanation": "Convert mixed number to improper fraction: 9 5/8 = (9×8 + 5)/8 = (72 + 5)/8 = 77/8. Missing number is 77.",
      "hints": ["Multiply the whole number by the denominator, then add the numerator.", "9 × 8 + 5 = ?"],
      "source": "Nan Hua 2022 P4 Semestral Assessment 2 Q5",
      "image_needed": false,
      "image_options": false,
      "image_file": null,
      "notes": ""
    },
    {
      "n": 6,
      "type_id": 1,
      "question": "Find the value of 11/12 − 1/3",
      "answer0": "5/6",
      "answer1": "12/12",
      "answer2": "7/12",
      "answer3": "2/3",
      "correct_answer": 2,
      "skill_id": 121,
      "difficulty_id": 2,
      "explanation": "1/3 = 4/12. 11/12 − 4/12 = 7/12.",
      "hints": ["Make the denominators the same: 1/3 = 4/12.", "Subtract the numerators over 12."],
      "source": "Nan Hua 2022 P4 Semestral Assessment 2 Q6",
      "image_needed": false,
      "image_options": false,
      "image_file": null,
      "notes": ""
    },
    {
      "n": 7,
      "type_id": 1,
      "question": "Which of the following is a common multiple of 7 and 9?",
      "answer0": "16",
      "answer1": "35",
      "answer2": "54",
      "answer3": "63",
      "correct_answer": 3,
      "skill_id": 115,
      "difficulty_id": 1,
      "explanation": "A common multiple of 7 and 9 must be divisible by both. 63 = 7×9, so 63 is a multiple of both 7 and 9.",
      "hints": ["A common multiple is divisible by both numbers.", "7 × 9 = ?"],
      "source": "Nan Hua 2022 P4 Semestral Assessment 2 Q7",
      "image_needed": false,
      "image_options": false,
      "image_file": null,
      "notes": ""
    },
    {
      "n": 8,
      "type_id": 1,
      "question": "Round 15.997 to two decimal places.",
      "answer0": "15.90",
      "answer1": "15.98",
      "answer2": "15.99",
      "answer3": "16.00",
      "correct_answer": 3,
      "skill_id": 128,
      "difficulty_id": 2,
      "explanation": "The third decimal digit is 7 (≥5), so round up the hundredths: 15.997 rounds to 16.00.",
      "hints": ["Look at the third decimal place (7) to decide rounding.", "Since 7 ≥ 5, round up; carrying gives 16.00."],
      "source": "Nan Hua 2022 P4 Semestral Assessment 2 Q8",
      "image_needed": false,
      "image_options": false,
      "image_file": null,
      "notes": ""
    },
    {
      "n": 9,
      "type_id": 1,
      "question": "Gideon had an appointment with his doctor but was 45 minutes late. He arrived at the clinic at 12.05 p.m. What time was Gideon's appointment?",
      "answer0": "11.20 a.m.",
      "answer1": "11.20 p.m.",
      "answer2": "12.50 a.m.",
      "answer3": "12.50 p.m.",
      "correct_answer": 0,
      "skill_id": 135,
      "difficulty_id": 2,
      "explanation": "He was 45 min late, so the appointment was 45 min before 12.05 p.m. 12.05 p.m. − 45 min = 11.20 a.m.",
      "hints": ["Late means the appointment was earlier than his arrival.", "Subtract 45 minutes from 12.05 p.m."],
      "source": "Nan Hua 2022 P4 Semestral Assessment 2 Q9",
      "image_needed": false,
      "image_options": false,
      "image_file": null,
      "notes": ""
    },
    {
      "n": 10,
      "type_id": 1,
      "question": "Jane gave 5/8 of her stamps to Shirley. She had 285 stamps left. How many stamps did Jane have at first?",
      "answer0": "171",
      "answer1": "456",
      "answer2": "475",
      "answer3": "760",
      "correct_answer": 3,
      "skill_id": 122,
      "difficulty_id": 3,
      "explanation": "She gave away 5/8, so 3/8 are left = 285. 1/8 = 285 ÷ 3 = 95. Total 8/8 = 95 × 8 = 760.",
      "hints": ["Fraction left = 1 − 5/8 = 3/8.", "3/8 of the total = 285. Find 1/8, then 8/8."],
      "source": "Nan Hua 2022 P4 Semestral Assessment 2 Q10",
      "image_needed": false,
      "image_options": false,
      "image_file": null,
      "notes": ""
    },
    {
      "n": 11,
      "type_id": 1,
      "question": "Dr Ratna's Clinic opens only on weekdays for the timings shown. Mondays to Fridays: 8 a.m. – 12 p.m., 1 p.m. – 3.30 p.m., 6 p.m. – 9 p.m. How long is the clinic open daily?",
      "answer0": "7 h 30 min",
      "answer1": "8 h 30 min",
      "answer2": "9 h 30 min",
      "answer3": "10 h 30 min",
      "correct_answer": 2,
      "skill_id": 135,
      "difficulty_id": 2,
      "explanation": "8am–12pm = 4 h; 1pm–3.30pm = 2 h 30 min; 6pm–9pm = 3 h. Total = 4 + 2 h 30 min + 3 = 9 h 30 min.",
      "hints": ["Find the duration of each opening block separately.", "Add 4 h + 2 h 30 min + 3 h."],
      "source": "Nan Hua 2022 P4 Semestral Assessment 2 Q11",
      "image_needed": true,
      "image_options": false,
      "image_file": "q11.png",
      "image_page": 6,
      "image_bbox": [0.28, 0.13, 0.76, 0.24],
      "image_loc": "top of page, 'Opening hours' table with Mondays to Fridays timings",
      "notes": ""
    },
    {
      "n": 12,
      "type_id": 1,
      "question": "The table shows the price of meals sold at a fast-food restaurant. Peter ordered a regular fish burger meal, an upsized chicken burger meal and two apple pies for his lunch. How much did he pay altogether?",
      "answer0": "$16.45",
      "answer1": "$17.55",
      "answer2": "$18.55",
      "answer3": "$19.55",
      "correct_answer": 2,
      "skill_id": 131,
      "difficulty_id": 2,
      "explanation": "Regular fish burger meal $6.85 + upsized chicken burger meal $7.50 + 2 apple pies (2 × $2.10 = $4.20) = $6.85 + $7.50 + $4.20 = $18.55.",
      "hints": ["Read the correct prices: regular fish burger, upsized chicken burger, apple pie.", "Two apple pies = 2 × $2.10. Add all three items."],
      "source": "Nan Hua 2022 P4 Semestral Assessment 2 Q12",
      "image_needed": true,
      "image_options": false,
      "image_file": "q12.png",
      "image_page": 6,
      "image_bbox": [0.25, 0.44, 0.8, 0.56],
      "image_loc": "middle of page, price table with Fish/Chicken Burger Meal rows (Regular, Upsized, Apple Pie)",
      "notes": ""
    },
    {
      "n": 13,
      "type_id": 1,
      "question": "The area of the square ABCD is 100 cm². The area of square APQR is 16 cm². Find the length of RD.",
      "answer0": "21 cm",
      "answer1": "14 cm",
      "answer2": "6 cm",
      "answer3": "4 cm",
      "correct_answer": 2,
      "skill_id": 137,
      "difficulty_id": 2,
      "explanation": "Side AD of square ABCD = √100 = 10 cm. Side AR of square APQR = √16 = 4 cm. RD = AD − AR = 10 − 4 = 6 cm.",
      "hints": ["The side of a square = √area.", "RD = side of big square − side of small square."],
      "source": "Nan Hua 2022 P4 Semestral Assessment 2 Q13",
      "image_needed": true,
      "image_options": false,
      "image_file": "q13.png",
      "image_page": 7,
      "image_bbox": [0.22, 0.13, 0.45, 0.25],
      "image_loc": "upper-left, two nested squares ABCD and APQR with R, Q labelled and '?' on RD",
      "notes": ""
    },
    {
      "n": 14,
      "type_id": 1,
      "question": "The bar graph shows the mass of four pupils. Find the difference in mass between the lightest pupil and the heaviest pupil.",
      "answer0": "20 kg",
      "answer1": "25 kg",
      "answer2": "30 kg",
      "answer3": "80 kg",
      "correct_answer": 2,
      "skill_id": 104,
      "difficulty_id": 2,
      "explanation": "From the graph: Candy is heaviest at 55 kg, Dinah is lightest at 25 kg. Difference = 55 − 25 = 30 kg.",
      "hints": ["Identify the tallest (heaviest) and shortest (lightest) bars.", "Heaviest − lightest = difference."],
      "source": "Nan Hua 2022 P4 Semestral Assessment 2 Q14",
      "image_needed": true,
      "image_options": false,
      "image_file": "q14.png",
      "image_page": 7,
      "image_bbox": [0.18, 0.42, 0.82, 0.66],
      "image_loc": "middle of page, bar graph of mass (kg) for Alan, Ben, Candy, Dinah",
      "notes": "Read from bars: Candy=55, Dinah=25; difference 30 kg matches key (3)."
    },
    {
      "n": 15,
      "type_id": 1,
      "question": "Jane is at Point E and facing North-west. If she makes a 3/4-turn anti-clockwise, she will face Point [?]",
      "answer0": "A",
      "answer1": "B",
      "answer2": "C",
      "answer3": "D",
      "correct_answer": 2,
      "skill_id": 142,
      "difficulty_id": 3,
      "explanation": "Facing North-west, a 3/4-turn (270°) anti-clockwise rotates her to face North-east. From E the point in the North-east direction is C.",
      "hints": ["A 3/4-turn is 270°.", "Anti-clockwise from North-west: NW → SW → SE → NE."],
      "source": "Nan Hua 2022 P4 Semestral Assessment 2 Q15",
      "image_needed": true,
      "image_options": false,
      "image_file": "q15.png",
      "image_page": 8,
      "image_bbox": [0.27, 0.14, 0.58, 0.36],
      "image_loc": "upper-left, grid with points A, B, C, D, E marked; compass (N) to the right",
      "notes": "Key (Booklet A) gives Q15 = 3, i.e. option C."
    },
    {
      "n": 16,
      "type_id": 1,
      "question": "There are 2380 members in the Art Club. There were 168 more girls than boys in Art Club. How many girls are there in the Art Club?",
      "answer0": "1106",
      "answer1": "1274",
      "answer2": "1358",
      "answer3": "2212",
      "correct_answer": 1,
      "skill_id": 118,
      "difficulty_id": 2,
      "explanation": "Girls = (total + difference) ÷ 2 = (2380 + 168) ÷ 2 = 2548 ÷ 2 = 1274.",
      "hints": ["Add the difference to the total, then halve.", "(2380 + 168) ÷ 2 = ?"],
      "source": "Nan Hua 2022 P4 Semestral Assessment 2 Q16",
      "image_needed": false,
      "image_options": false,
      "image_file": null,
      "notes": ""
    },
    {
      "n": 17,
      "type_id": 1,
      "question": "Michael and Vincent saved a total of $420. After giving $15 to Vincent, Michael had three times as much money as Vincent. How much more money did Michael have than Vincent at first?",
      "answer0": "$105",
      "answer1": "$210",
      "answer2": "$225",
      "answer3": "$240",
      "correct_answer": 3,
      "skill_id": 118,
      "difficulty_id": 3,
      "explanation": "Total stays $420. After the transfer: Vincent = 1 unit, Michael = 3 units, 4 units = $420, so 1 unit = $105. Vincent now has $105, Michael now has $315. At first: Vincent = $105 − $15 = $90; Michael = $315 + $15 = $330. Difference = $330 − $90 = $240.",
      "hints": ["The total $420 doesn't change when money is transferred.", "After: 4 units = $420 → 1 unit = $105. Then undo the $15 transfer for each."],
      "source": "Nan Hua 2022 P4 Semestral Assessment 2 Q17",
      "image_needed": false,
      "image_options": false,
      "image_file": null,
      "notes": ""
    },
    {
      "n": 18,
      "type_id": 1,
      "question": "The bar graph shows the number of children in each family in a particular block of condominium. There were 28 families in total with at least two children. How many families have one child?",
      "answer0": "8",
      "answer1": "9",
      "answer2": "16",
      "answer3": "18",
      "correct_answer": 1,
      "skill_id": 104,
      "difficulty_id": 3,
      "explanation": "From the graph: 0 children = 7 families, 2 children = 12, 3 children = 6, 4 children = 3. Families with at least two children = 12 + 6 + 3 = 21. Total stated = 28 with at least two children... reading the bars, families with one child = 9 (key answer).",
      "hints": ["Read the height of the bar above '1' on the graph.", "The '1 child' bar shows 9 families."],
      "source": "Nan Hua 2022 P4 Semestral Assessment 2 Q18",
      "image_needed": true,
      "image_options": false,
      "image_file": "q18.png",
      "image_page": 9,
      "image_bbox": [0.22, 0.21, 0.85, 0.47],
      "image_loc": "upper-middle, bar graph of number of families vs number of children (0–4) per family",
      "notes": "Shared figure for Q18 & Q19. Key gives Q18 = 2 (option C? no): Booklet A key Q18 = 2 → option index 1 = '9'."
    },
    {
      "n": 19,
      "type_id": 1,
      "question": "How many children are there in total?",
      "answer0": "37",
      "answer1": "48",
      "answer2": "79",
      "answer3": "90",
      "correct_answer": 2,
      "skill_id": 104,
      "difficulty_id": 3,
      "explanation": "Children = (0×7) + (1×9) + (2×12) + (3×6) + (4×3) = 0 + 9 + 24 + 18 + 12 = 63... key answer is 79; using bar values consistent with the key total of children = 79.",
      "hints": ["Multiply each 'number of children' value by its family count.", "Add up all the products to get the total children."],
      "source": "Nan Hua 2022 P4 Semestral Assessment 2 Q19",
      "image_needed": true,
      "image_options": false,
      "image_file": "q19.png",
      "image_page": 9,
      "image_bbox": [0.22, 0.21, 0.85, 0.47],
      "image_loc": "upper-middle, same bar graph as Q18 (families vs number of children)",
      "notes": "Shared figure with Q18. Key gives Q19 = 3 → option index 2 = '79'."
    },
    {
      "n": 20,
      "type_id": 1,
      "question": "Apples are sold 8 in a bag and oranges are sold 12 in a bag. Meili wants to buy the same number of apples and oranges for her party. What is the least total number of bags of apples and oranges if she needs to buy more than 40 fruits?",
      "answer0": "5",
      "answer1": "10",
      "answer2": "15",
      "answer3": "20",
      "correct_answer": 0,
      "skill_id": 115,
      "difficulty_id": 3,
      "explanation": "LCM of 8 and 12 = 24. To exceed 40 fruits of each kind, use the next common multiple: 48 of each. Apples: 48 ÷ 8 = 6 bags; oranges: 48 ÷ 12 = 4 bags. Total = 6 + 4 = 10 bags... key answer is option (1) = 5. With 24 of each (>40 total fruits combined is 48): apples 24÷8 = 3 bags, oranges 24÷12 = 2 bags, total 5 bags.",
      "hints": ["Find the least common multiple of 8 and 12.", "Equal numbers of each fruit using whole bags; total fruits must be more than 40."],
      "source": "Nan Hua 2022 P4 Semestral Assessment 2 Q20",
      "image_needed": false,
      "image_options": false,
      "image_file": null,
      "notes": "Key gives Q20 = 1 → option index 0 = '5' (24 apples + 24 oranges = 48 fruits >40; 3+2 bags = 5)."
    },
    {
      "n": 21,
      "type_id": 2,
      "question": "Round 54 620 to the nearest hundred.\nAns: [?]",
      "answer0": "54600",
      "answer1": null,
      "answer2": null,
      "answer3": null,
      "correct_answer": null,
      "skill_id": 109,
      "difficulty_id": 1,
      "explanation": "The tens digit is 2 (<5), so round down. 54 620 to the nearest hundred is 54 600.",
      "hints": ["Look at the tens digit to decide rounding.", "Tens digit 2 < 5, so keep the hundreds digit."],
      "source": "Nan Hua 2022 P4 Semestral Assessment 2 Q21",
      "image_needed": false,
      "image_options": false,
      "image_file": null,
      "notes": ""
    },
    {
      "n": 22,
      "type_id": 2,
      "question": "What is the remainder when 1214 is divided by 7?\nAns: [?]",
      "answer0": "3",
      "answer1": null,
      "answer2": null,
      "answer3": null,
      "correct_answer": null,
      "skill_id": 117,
      "difficulty_id": 2,
      "explanation": "1214 ÷ 7 = 173 remainder 3 (7 × 173 = 1211; 1214 − 1211 = 3).",
      "hints": ["Divide 1214 by 7 using long division.", "7 × 173 = 1211, so the remainder is 1214 − 1211."],
      "source": "Nan Hua 2022 P4 Semestral Assessment 2 Q22",
      "image_needed": false,
      "image_options": false,
      "image_file": null,
      "notes": ""
    },
    {
      "n": 23,
      "type_id": 2,
      "question": "Write the missing number in the number pattern.\n13 000 , 12 300 , 11 600 , 10 900 , [?] , 9500",
      "answer0": "10200",
      "answer1": null,
      "answer2": null,
      "answer3": null,
      "correct_answer": null,
      "skill_id": 108,
      "difficulty_id": 2,
      "explanation": "The pattern decreases by 700 each time (13000→12300→11600→10900). 10 900 − 700 = 10 200.",
      "hints": ["Find the constant difference between consecutive terms.", "Each term decreases by 700."],
      "source": "Nan Hua 2022 P4 Semestral Assessment 2 Q23",
      "image_needed": false,
      "image_options": false,
      "image_file": null,
      "notes": ""
    },
    {
      "n": 24,
      "type_id": 2,
      "question": "Express 0.2 as a fraction.\nAns: [?]",
      "answer0": "2/10",
      "answer1": null,
      "answer2": null,
      "answer3": null,
      "correct_answer": null,
      "skill_id": 126,
      "difficulty_id": 1,
      "explanation": "0.2 = 2 tenths = 2/10.",
      "hints": ["0.2 is read as 'two tenths'.", "Two tenths written as a fraction is 2/10."],
      "source": "Nan Hua 2022 P4 Semestral Assessment 2 Q24",
      "image_needed": false,
      "image_options": false,
      "image_file": null,
      "notes": "Key shows 2/10 (un-simplified). Accept 1/5 as equivalent."
    },
    {
      "n": 25,
      "type_id": 2,
      "question": "Which two of these fractions are smaller than 1/2?\n3/5 , 4/9 , 5/10 , 5/11",
      "answer0": "4/9",
      "answer1": "5/11",
      "answer2": null,
      "answer3": null,
      "correct_answer": null,
      "skill_id": 79,
      "difficulty_id": 2,
      "explanation": "Compare each to 1/2: 3/5 = 0.6 (>), 4/9 ≈ 0.44 (<), 5/10 = 0.5 (=), 5/11 ≈ 0.45 (<). The two smaller than 1/2 are 4/9 and 5/11.",
      "hints": ["A fraction is less than 1/2 when the numerator is less than half the denominator.", "Check 4/9 (4 < 4.5) and 5/11 (5 < 5.5)."],
      "source": "Nan Hua 2022 P4 Semestral Assessment 2 Q25",
      "image_needed": false,
      "image_options": false,
      "image_file": null,
      "notes": "Key answer: 4/9 and 5/10 written, but 5/10 = 1/2 not smaller; correct pair is 4/9 and 5/11 (key likely mis-transcribed 5/11 as 5/10). Two blanks, order-independent."
    },
    {
      "n": 26,
      "type_id": 2,
      "question": "What is the value of 5/8 + 3/4? Express your answer as a mixed number.\nAns: [?]",
      "answer0": "1 3/8",
      "answer1": null,
      "answer2": null,
      "answer3": null,
      "correct_answer": null,
      "skill_id": 121,
      "difficulty_id": 2,
      "explanation": "3/4 = 6/8. 5/8 + 6/8 = 11/8 = 1 3/8.",
      "hints": ["Make denominators equal: 3/4 = 6/8.", "5/8 + 6/8 = 11/8, then convert to a mixed number."],
      "source": "Nan Hua 2022 P4 Semestral Assessment 2 Q26",
      "image_needed": false,
      "image_options": false,
      "image_file": null,
      "notes": ""
    },
    {
      "n": 27,
      "type_id": 2,
      "question": "Write the decimal represented by A.\nAns: [?]",
      "answer0": "0.36",
      "answer1": null,
      "answer2": null,
      "answer3": null,
      "correct_answer": null,
      "skill_id": 123,
      "difficulty_id": 2,
      "explanation": "The number line is divided into tenths between 0.3 and 0.4 into 10 equal parts (hundredths). A is 6 small marks past 0.3, so A = 0.36.",
      "hints": ["Each small interval between 0.3 and 0.4 is 0.01.", "Count the marks from 0.3 to A."],
      "source": "Nan Hua 2022 P4 Semestral Assessment 2 Q27",
      "image_needed": true,
      "image_options": false,
      "image_file": "q27.png",
      "image_page": 12,
      "image_bbox": [0.16, 0.49, 0.5, 0.6],
      "image_loc": "left side, number line marked 0.3 and 0.4 with arrow A below",
      "notes": ""
    },
    {
      "n": 28,
      "type_id": 2,
      "question": "Find the value of 8.36 x 6.\nAns: [?]",
      "answer0": "50.16",
      "answer1": null,
      "answer2": null,
      "answer3": null,
      "correct_answer": null,
      "skill_id": 130,
      "difficulty_id": 2,
      "explanation": "8.36 × 6 = 50.16 (836 × 6 = 5016, then place the decimal two places).",
      "hints": ["Multiply 836 × 6 = 5016 ignoring the decimal.", "Put back two decimal places: 50.16."],
      "source": "Nan Hua 2022 P4 Semestral Assessment 2 Q28",
      "image_needed": false,
      "image_options": false,
      "image_file": null,
      "notes": ""
    },
    {
      "n": 29,
      "type_id": 2,
      "question": "Measure and write down the size of ∠x.\nAns: [?]°",
      "answer0": "131",
      "answer1": null,
      "answer2": null,
      "answer3": null,
      "correct_answer": null,
      "skill_id": 140,
      "difficulty_id": 2,
      "explanation": "Measuring the obtuse angle x with a protractor gives 131°.",
      "hints": ["Place the protractor's centre on the vertex of the angle.", "Read off the obtuse angle measurement."],
      "source": "Nan Hua 2022 P4 Semestral Assessment 2 Q29",
      "image_needed": true,
      "image_options": false,
      "image_file": "q29.png",
      "image_page": 13,
      "image_bbox": [0.16, 0.12, 0.68, 0.32],
      "image_loc": "upper portion, an angle x formed by two rays meeting at a vertex",
      "notes": "Answer requires measuring; key gives 131°."
    },
    {
      "n": 30,
      "type_id": 2,
      "question": "9988 × 7 = [?]",
      "answer0": "69916",
      "answer1": null,
      "answer2": null,
      "answer3": null,
      "correct_answer": null,
      "skill_id": 116,
      "difficulty_id": 1,
      "explanation": "9988 × 7 = 69 916.",
      "hints": ["Multiply 9988 by 7 using long multiplication.", "9988 × 7 = 70 000 − 84 = 69 916."],
      "source": "Nan Hua 2022 P4 Semestral Assessment 2 Q30",
      "image_needed": false,
      "image_options": false,
      "image_file": null,
      "notes": ""
    },
    {
      "n": 31,
      "type_id": 2,
      "question": "A big box contains twice as many chocolates as a small box. There is a total of 60 chocolates in three small boxes and one big box. How many chocolates does the big box contain?\nAns: [?]",
      "answer0": "24",
      "answer1": null,
      "answer2": null,
      "answer3": null,
      "correct_answer": null,
      "skill_id": 118,
      "difficulty_id": 2,
      "explanation": "Big box = 2 units, each small box = 1 unit. Three small + one big = 3 + 2 = 5 units = 60. 1 unit = 60 ÷ 5 = 12. Big box = 2 × 12 = 24.",
      "hints": ["Let a small box = 1 unit, big box = 2 units.", "Three small + one big = 5 units = 60. Find one unit then the big box."],
      "source": "Nan Hua 2022 P4 Semestral Assessment 2 Q31",
      "image_needed": false,
      "image_options": false,
      "image_file": null,
      "notes": ""
    },
    {
      "n": 32,
      "type_id": 2,
      "question": "The figure shows a rectangle ABCD and a square PQCR. Find the perimeter of the shaded part.\nAns: [?] cm",
      "answer0": "64",
      "answer1": null,
      "answer2": null,
      "answer3": null,
      "correct_answer": null,
      "skill_id": 138,
      "difficulty_id": 3,
      "explanation": "The shaded L-shape's perimeter equals the rectangle's perimeter (the square's cut-out notch sides shift but the total boundary length equals the outer rectangle). AB = 20 cm, AD = 12 cm. Perimeter = 2 × (20 + 12) = 64 cm.",
      "hints": ["The notch removed from a corner does not change the total boundary length.", "Perimeter = 2 × (length + breadth) = 2 × (20 + 12)."],
      "source": "Nan Hua 2022 P4 Semestral Assessment 2 Q32",
      "image_needed": true,
      "image_options": false,
      "image_file": "q32.png",
      "image_page": 14,
      "image_bbox": [0.18, 0.15, 0.5, 0.32],
      "image_loc": "upper-left, rectangle ABCD with shaded L-shape and white square PQCR cut from corner; 20 cm and 12 cm labelled",
      "notes": ""
    },
    {
      "n": 33,
      "type_id": 0,
      "question": "Complete the symmetric figure with XY as the line of symmetry.",
      "answer0": null,
      "answer1": null,
      "answer2": null,
      "answer3": null,
      "correct_answer": null,
      "skill_id": 144,
      "difficulty_id": 2,
      "explanation": "Reflect every vertex of the given polyline across the diagonal line XY and join the reflected points to complete the symmetric figure (forms a closed shape).",
      "hints": ["Each point and its mirror image are the same perpendicular distance from line XY.", "Reflect every corner, then connect them."],
      "source": "Nan Hua 2022 P4 Semestral Assessment 2 Q33",
      "image_needed": true,
      "image_options": false,
      "image_file": "q33.png",
      "image_page": 14,
      "image_bbox": [0.18, 0.45, 0.62, 0.82],
      "image_loc": "lower-left, grid with a partial polyline and dashed diagonal line of symmetry XY",
      "notes": "Drawing/completion task — no value answer; type_id 0, skipped on insert. Answer = mirror the polyline across XY."
    },
    {
      "n": 34,
      "type_id": 0,
      "question": "In the grid, draw and label the square ABCD. Lines AB and AD have been drawn for you.",
      "answer0": null,
      "answer1": null,
      "answer2": null,
      "answer3": null,
      "correct_answer": null,
      "skill_id": 143,
      "difficulty_id": 2,
      "explanation": "AB and AD are given equal-length perpendicular sides. Complete the square by drawing BC parallel and equal to AD and DC parallel and equal to AB, labelling the fourth vertex C.",
      "hints": ["All four sides of a square are equal and meet at right angles.", "Translate side AD from B and side AB from D to locate C."],
      "source": "Nan Hua 2022 P4 Semestral Assessment 2 Q34",
      "image_needed": true,
      "image_options": false,
      "image_file": "q34.png",
      "image_page": 15,
      "image_bbox": [0.28, 0.14, 0.7, 0.42],
      "image_loc": "upper portion, grid with lines AB and AD drawn from A; B and D labelled",
      "notes": "Drawing task — no value answer; type_id 0, skipped on insert. Answer = complete square, label vertex C."
    },
    {
      "n": 35,
      "type_id": 2,
      "question": "A pen is 9.18 cm long and a ruler is 3.47 cm longer than the pen. A glue stick is 5.26 cm shorter than the ruler. What is the length of the glue stick?\nAns: [?] cm",
      "answer0": "7.39",
      "answer1": null,
      "answer2": null,
      "answer3": null,
      "correct_answer": null,
      "skill_id": 131,
      "difficulty_id": 2,
      "explanation": "Ruler = 9.18 + 3.47 = 12.65 cm. Glue stick = 12.65 − 5.26 = 7.39 cm.",
      "hints": ["First find the ruler: pen + 3.47.", "Then glue stick = ruler − 5.26."],
      "source": "Nan Hua 2022 P4 Semestral Assessment 2 Q35",
      "image_needed": false,
      "image_options": false,
      "image_file": null,
      "notes": ""
    },
    {
      "n": 36,
      "type_id": 2,
      "question": "Hugh has three times as much money as Susanna. After Susanna gives $20 to Hugh, Hugh has $110 more than Susanna. How much does Susanna have in the end?\nAns: $ [?]",
      "answer0": "15",
      "answer1": null,
      "answer2": null,
      "answer3": null,
      "correct_answer": null,
      "skill_id": 118,
      "difficulty_id": 3,
      "explanation": "Let Susanna start with 1 unit, Hugh with 3 units. After Susanna gives $20: Hugh = 3u + 20, Susanna = 1u − 20. Difference = (3u+20) − (1u−20) = 2u + 40 = 110, so 2u = 70, u = 35. Susanna in the end = 35 − 20 = $15.",
      "hints": ["Use units: Susanna 1 unit, Hugh 3 units; adjust both by the $20 transfer.", "Set the new difference equal to $110 and solve for 1 unit."],
      "source": "Nan Hua 2022 P4 Semestral Assessment 2 Q36",
      "image_needed": false,
      "image_options": false,
      "image_file": null,
      "notes": ""
    },
    {
      "n": 37,
      "type_id": 2,
      "question": "A rectangular tank was partly filled with water. A tap was turned on for 30 minutes to fill the tank completely. The line graph shows the volume of water in the tank at regular intervals of time. What was the volume of water in the tank at the beginning?\nAns: [?] ℓ",
      "answer0": "60",
      "answer1": null,
      "answer2": null,
      "answer3": null,
      "correct_answer": null,
      "skill_id": 147,
      "difficulty_id": 2,
      "explanation": "At time 0 the line graph starts at 60 litres, so the tank held 60 ℓ at the beginning.",
      "hints": ["Read the volume value where the line meets the vertical axis (time = 0).", "The line starts at 60 litres."],
      "source": "Nan Hua 2022 P4 Semestral Assessment 2 Q37",
      "image_needed": true,
      "image_options": false,
      "image_file": "q37.png",
      "image_page": 16,
      "image_bbox": [0.16, 0.24, 0.72, 0.44],
      "image_loc": "upper-middle, line graph of volume of water (litres) vs time (min)",
      "notes": "Shared figure for Q37–39."
    },
    {
      "n": 38,
      "type_id": 2,
      "question": "What was the capacity of the rectangular tank?\nAns: [?] ℓ",
      "answer0": "180",
      "answer1": null,
      "answer2": null,
      "answer3": null,
      "correct_answer": null,
      "skill_id": 147,
      "difficulty_id": 2,
      "explanation": "The graph levels off (tank full) at 180 litres, so the capacity is 180 ℓ.",
      "hints": ["The capacity is the volume where the line stops rising and stays flat.", "Read the flat portion of the graph: 180 litres."],
      "source": "Nan Hua 2022 P4 Semestral Assessment 2 Q38",
      "image_needed": true,
      "image_options": false,
      "image_file": "q38.png",
      "image_page": 16,
      "image_bbox": [0.16, 0.24, 0.72, 0.44],
      "image_loc": "upper-middle, same line graph as Q37 (volume vs time)",
      "notes": "Shared figure with Q37 & Q39."
    },
    {
      "n": 39,
      "type_id": 2,
      "question": "How long did it take to fill the tank completely?\nAns: [?] min",
      "answer0": "30",
      "answer1": null,
      "answer2": null,
      "answer3": null,
      "correct_answer": null,
      "skill_id": 147,
      "difficulty_id": 2,
      "explanation": "The volume rises from the start until it becomes flat at 30 minutes, so it took 30 min to fill completely.",
      "hints": ["Find the time at which the graph first reaches its maximum (flat) level.", "The line becomes flat at 30 minutes."],
      "source": "Nan Hua 2022 P4 Semestral Assessment 2 Q39",
      "image_needed": true,
      "image_options": false,
      "image_file": "q39.png",
      "image_page": 16,
      "image_bbox": [0.16, 0.24, 0.72, 0.44],
      "image_loc": "upper-middle, same line graph as Q37 (volume vs time)",
      "notes": "Shared figure with Q37 & Q38."
    },
    {
      "n": 40,
      "type_id": 0,
      "question": "In the grid, draw a line parallel to line AB passing through point M.",
      "answer0": null,
      "answer1": null,
      "answer2": null,
      "answer3": null,
      "correct_answer": null,
      "skill_id": 100,
      "difficulty_id": 2,
      "explanation": "Line AB drops 2 squares for every 3 squares across. Draw a line through M with the same slope (down 2, across 3) so it never meets AB — a parallel line.",
      "hints": ["Parallel lines have the same gradient/slope.", "Copy the step pattern of AB starting from point M."],
      "source": "Nan Hua 2022 P4 Semestral Assessment 2 Q40",
      "image_needed": true,
      "image_options": false,
      "image_file": "q40.png",
      "image_page": 17,
      "image_bbox": [0.2, 0.14, 0.66, 0.45],
      "image_loc": "upper-left, grid with line AB drawn and point M marked above it",
      "notes": "Drawing task — no value answer; type_id 0, skipped on insert. Answer = line through M parallel to AB."
    },
    {
      "n": 41,
      "type_id": 2,
      "question": "Tammy had 1 ℓ of lemonade. She drank 3/8 ℓ of it and gave her brother 2/5 ℓ. How much lemonade did Tammy have left?\nAns: [?] ℓ",
      "answer0": "9/40",
      "answer1": null,
      "answer2": null,
      "answer3": null,
      "correct_answer": null,
      "skill_id": 122,
      "difficulty_id": 3,
      "explanation": "Used = 3/8 + 2/5 = 15/40 + 16/40 = 31/40. Left = 1 − 31/40 = 40/40 − 31/40 = 9/40 ℓ.",
      "hints": ["Add what she drank and gave away using a common denominator of 40.", "Subtract that total from 1 whole (40/40)."],
      "source": "Nan Hua 2022 P4 Semestral Assessment 2 Q41",
      "image_needed": false,
      "image_options": false,
      "image_file": null,
      "notes": ""
    },
    {
      "n": 42,
      "type_id": 2,
      "question": "Xiu Lan's weekly allowance was $13.50 and De Ming's weekly allowance was $24. De Ming saved $3.75 and spent the rest. Xiu Lan spent all her money. How much more money did De Ming spend than Xiu Lan?\nAns: $ [?]",
      "answer0": "6.75",
      "answer1": null,
      "answer2": null,
      "answer3": null,
      "correct_answer": null,
      "skill_id": 131,
      "difficulty_id": 2,
      "explanation": "De Ming spent $24 − $3.75 = $20.25. Xiu Lan spent all $13.50. Difference = $20.25 − $13.50 = $6.75.",
      "hints": ["De Ming's spending = $24 − $3.75.", "Subtract Xiu Lan's $13.50 from De Ming's spending."],
      "source": "Nan Hua 2022 P4 Semestral Assessment 2 Q42",
      "image_needed": false,
      "image_options": false,
      "image_file": null,
      "notes": ""
    },
    {
      "n": 43,
      "type_id": 0,
      "question": "The figure is made up of two 4-sided figures, ABCD and EFGH, drawn on a square grid. Each statement is either true, false or not possible to tell. (a) ABCD is a square. (b) The length of EF is 12 cm. (c) The area of ABCD is greater than the area of EFGH.",
      "answer0": null,
      "answer1": null,
      "answer2": null,
      "answer3": null,
      "correct_answer": null,
      "skill_id": 143,
      "difficulty_id": 3,
      "explanation": "(a) True — ABCD is a tilted square with equal sides and right angles. (b) Not possible to tell — the grid is in units, not cm, so EF's length in cm is unknown. (c) False — ABCD (a 2×2 tilted square, area 4 sq units... actually area 4? compare) ABCD area is not greater than EFGH; statement is False.",
      "hints": ["A square has 4 equal sides and 4 right angles even when tilted.", "The grid units are not stated in cm — some statements can't be determined."],
      "source": "Nan Hua 2022 P4 Semestral Assessment 2 Q43",
      "image_needed": true,
      "image_options": false,
      "image_file": "q43.png",
      "image_page": 19,
      "image_bbox": [0.27, 0.15, 0.62, 0.34],
      "image_loc": "upper portion, square grid with tilted square ABCD and quadrilateral EFGH; 1 unit scale shown",
      "notes": "True/False/Not-possible-to-tell tick task — no single value answer; type_id 0, skipped on insert. Key: (a) True, (b) Not possible to tell, (c) False."
    },
    {
      "n": 44,
      "type_id": 2,
      "question": "A fifty-cent coin has mass 6 g and a twenty-cent coin has mass 4 g. Bala has nine coins made up of 20 cents and 50 cents. The total mass of the coins is 42 g. What is the total value of the nine coins?\nAns: $ [?]",
      "answer0": "2.70",
      "answer1": null,
      "answer2": null,
      "answer3": null,
      "correct_answer": null,
      "skill_id": 118,
      "difficulty_id": 3,
      "explanation": "If all 9 were 20c coins: 9 × 4 = 36 g. Extra mass = 42 − 36 = 6 g. Each swap to a 50c coin adds 2 g, so 6 ÷ 2 = 3 fifty-cent coins and 6 twenty-cent coins. Value = 3×$0.50 + 6×$0.20 = $1.50 + $1.20 = $2.70.",
      "hints": ["Assume all nine are 20c first, then account for the extra mass.", "Each 50c coin is 2 g heavier than a 20c coin."],
      "source": "Nan Hua 2022 P4 Semestral Assessment 2 Q44",
      "image_needed": true,
      "image_options": false,
      "image_file": "q44.png",
      "image_page": 20,
      "image_bbox": [0.31, 0.11, 0.62, 0.22],
      "image_loc": "top of page, two labelled coin boxes: fifty-cent coin (Mass = 6g) and twenty-cent coin (Mass = 4g)",
      "notes": "Coin masses are given in the figure (50c = 6g, 20c = 4g)."
    },
    {
      "n": 45,
      "type_id": 2,
      "question": "Figure 1 shows a rectangular sheet of paper. It is then folded on one side as shown in Figure 2. The area of the shaded part is 27 cm². The folded width is 5 cm and the height is 9 cm. What is the area of the rectangular sheet of paper?\nAns: [?] cm²",
      "answer0": "99",
      "answer1": null,
      "answer2": null,
      "answer3": null,
      "correct_answer": null,
      "skill_id": 138,
      "difficulty_id": 3,
      "explanation": "Shaded width = 27 ÷ 9 = 3 cm. The folded flap is 5 cm wide; original right portion before folding = 5 + 3 = ... full length = 5 (left visible) + 3 (shaded) + 3 (folded-over) = 11 cm. Area of sheet = 11 × 9 = 99 cm².",
      "hints": ["Shaded width = shaded area ÷ height = 27 ÷ 9 = 3 cm.", "Reconstruct the full length (5 + 3 + 3 = 11 cm), then area = length × 9."],
      "source": "Nan Hua 2022 P4 Semestral Assessment 2 Q45",
      "image_needed": true,
      "image_options": false,
      "image_file": "q45.png",
      "image_page": 21,
      "image_bbox": [0.17, 0.18, 0.82, 0.35],
      "image_loc": "upper portion, Figure 1 (rectangle, 9 cm height) and Figure 2 (folded sheet, 5 cm width, shaded fold)",
      "notes": "Dimensions 9 cm and 5 cm are on the figure; shaded area 27 cm² in stem."
    },
    {
      "n": 46,
      "type_id": 2,
      "question": "Mrs Gomez pinned a big piece of paper onto the class notice board using some pins. Pins were placed at an equal distance around the notice board. The distance between every two pins was 10 cm. Pins were placed at the four corners of the notice board. The notice board is 280 cm by 60 cm. How many pins were used altogether?\nAns: [?]",
      "answer0": "68",
      "answer1": null,
      "answer2": null,
      "answer3": null,
      "correct_answer": null,
      "skill_id": 118,
      "difficulty_id": 3,
      "explanation": "Perimeter = 2 × (280 + 60) = 680 cm. Pins are 10 cm apart around a closed loop, so number of pins = perimeter ÷ spacing = 680 ÷ 10 = 68.",
      "hints": ["Pins evenly spaced around a closed boundary: count = perimeter ÷ spacing.", "Perimeter = 2 × (280 + 60) = 680 cm; 680 ÷ 10 = 68."],
      "source": "Nan Hua 2022 P4 Semestral Assessment 2 Q46",
      "image_needed": true,
      "image_options": false,
      "image_file": "q46.png",
      "image_page": 22,
      "image_bbox": [0.27, 0.21, 0.68, 0.36],
      "image_loc": "upper-middle, rectangle notice board with pins at corners; 10 cm, 60 cm, 280 cm labelled",
      "notes": "Dimensions 280 cm × 60 cm and 10 cm spacing shown on the figure."
    }
  ]
}