{
 "paper": {
  "school": "Ai Tong",
  "year": 2024,
  "level": "P4",
  "label": "End-of-Year Exam",
  "source_prefix": "Ai Tong 2024 P4 End-of-Year Exam",
  "has_answer_key": true
 },
 "questions": [
  {
   "n": 1,
   "type_id": 1,
   "question": "44 thousands and 3 tens is the same as [?]",
   "answer0": "443",
   "answer1": "4430",
   "answer2": "44 003",
   "answer3": "44 030",
   "correct_answer": 3,
   "skill_id": 105,
   "difficulty_id": 1,
   "explanation": "44 thousands = 44 000 and 3 tens = 30. Total = 44 000 + 30 = 44 030.",
   "hints": [
    "1 thousand = 1000, 1 ten = 10.",
    "44 thousands = 44 000; 3 tens = 30; add them."
   ],
   "source": "Ai Tong 2024 P4 End-of-Year Exam Q1",
   "image_needed": false,
   "image_options": false,
   "image_file": null,
   "notes": "Key: option 4 (44 030)."
  },
  {
   "n": 2,
   "type_id": 1,
   "question": "12 658 rounded to the nearest hundred is [?]",
   "answer0": "13 000",
   "answer1": "12 700",
   "answer2": "12 660",
   "answer3": "12 600",
   "correct_answer": 1,
   "skill_id": 109,
   "difficulty_id": 1,
   "explanation": "The tens digit is 5, so round up: 12 658 rounds to 12 700.",
   "hints": [
    "Look at the tens digit (5). 5 or more rounds up.",
    "12 658 -> 12 700."
   ],
   "source": "Ai Tong 2024 P4 End-of-Year Exam Q2",
   "image_needed": false,
   "image_options": false,
   "image_file": null,
   "notes": "Key: option 2 (12 700)."
  },
  {
   "n": 3,
   "type_id": 1,
   "question": "$$7\\frac{5}{8}$$ = $$\\frac{[?]}{8}$$<br>What is the missing number in the box?",
   "answer0": "35",
   "answer1": "51",
   "answer2": "56",
   "answer3": "61",
   "correct_answer": 3,
   "skill_id": 119,
   "difficulty_id": 2,
   "explanation": "Convert the mixed number to an improper fraction: 7 x 8 + 5 = 61. So $$7\\frac{5}{8}=\\frac{61}{8}$$.",
   "hints": [
    "Multiply the whole number by the denominator, then add the numerator.",
    "7 x 8 = 56; 56 + 5 = 61."
   ],
   "source": "Ai Tong 2024 P4 End-of-Year Exam Q3",
   "image_needed": false,
   "image_options": false,
   "image_file": null,
   "notes": "Key: option 4 (61)."
  },
  {
   "n": 4,
   "type_id": 1,
   "question": "Express $$\\frac{74}{100}$$ as a decimal.",
   "answer0": "0.704",
   "answer1": "0.074",
   "answer2": "0.74",
   "answer3": "7.04",
   "correct_answer": 2,
   "skill_id": 127,
   "difficulty_id": 1,
   "explanation": "74 hundredths = 0.74.",
   "hints": [
    "Hundredths go to 2 decimal places.",
    "74/100 = 0.74."
   ],
   "source": "Ai Tong 2024 P4 End-of-Year Exam Q4",
   "image_needed": false,
   "image_options": false,
   "image_file": null,
   "notes": "Key: option 3 (0.74)."
  },
  {
   "n": 5,
   "type_id": 1,
   "question": "Which number is 2.1 less than 9.37?",
   "answer0": "7.27",
   "answer1": "9.16",
   "answer2": "9.58",
   "answer3": "11.47",
   "correct_answer": 0,
   "skill_id": 129,
   "difficulty_id": 2,
   "explanation": "9.37 - 2.1 = 7.27.",
   "hints": [
    "Subtract 2.1 from 9.37.",
    "Line up the decimal points: 9.37 - 2.10 = 7.27."
   ],
   "source": "Ai Tong 2024 P4 End-of-Year Exam Q5",
   "image_needed": false,
   "image_options": false,
   "image_file": null,
   "notes": "Key: option 1 (7.27)."
  },
  {
   "n": 6,
   "type_id": 1,
   "question": "Which of the following is a factor of both 12 and 28?",
   "answer0": "8",
   "answer1": "7",
   "answer2": "6",
   "answer3": "4",
   "correct_answer": 3,
   "skill_id": 113,
   "difficulty_id": 2,
   "explanation": "Factors of 12: 1, 2, 3, 4, 6, 12. Factors of 28: 1, 2, 4, 7, 14, 28. The common factor among the options is 4.",
   "hints": [
    "List the factors of each number.",
    "4 divides both 12 and 28."
   ],
   "source": "Ai Tong 2024 P4 End-of-Year Exam Q6",
   "image_needed": false,
   "image_options": false,
   "image_file": null,
   "notes": "Key: option 4 (4)."
  },
  {
   "n": 7,
   "type_id": 1,
   "question": "Arrange the following decimals from the smallest to the greatest.<br>3.504 , 0.354 , 35.4 , 35.04",
   "answer0": "0.354 , 3.504 , 35.04 , 35.4",
   "answer1": "0.354 , 3.504 , 35.4 , 35.04",
   "answer2": "35.04 , 35.4 , 3.504 , 0.354",
   "answer3": "35.4 , 35.04 , 3.504 , 0.354",
   "correct_answer": 0,
   "skill_id": 124,
   "difficulty_id": 2,
   "explanation": "Compare whole-number parts then decimals: 0.354 < 3.504 < 35.04 < 35.4.",
   "hints": [
    "Compare the whole-number parts first.",
    "35.04 has 0 tenths, 35.4 has 4 tenths, so 35.04 < 35.4."
   ],
   "source": "Ai Tong 2024 P4 End-of-Year Exam Q7",
   "image_needed": false,
   "image_options": false,
   "image_file": null,
   "notes": "Key: option 1 (0.354, 3.504, 35.04, 35.4)."
  },
  {
   "n": 8,
   "type_id": 1,
   "question": "Which of the following figures has more than 2 pairs of parallel lines?",
   "answer0": "Figure 1",
   "answer1": "Figure 2",
   "answer2": "Figure 3",
   "answer3": "Figure 4",
   "correct_answer": 0,
   "skill_id": 100,
   "difficulty_id": 3,
   "explanation": "Figure 1 (the arrow/pentagon shape made of a rectangle with a notch) has more than 2 pairs of parallel sides; the trapezium (2), parallelogram (3) and triangle (4) have at most 2 pairs.",
   "hints": [
    "Count pairs of parallel sides in each shape.",
    "A parallelogram has only 2 pairs; look for the figure with more."
   ],
   "source": "Ai Tong 2024 P4 End-of-Year Exam Q8",
   "image_needed": true,
   "image_options": true,
   "image_file": null,
   "image_page": 5,
   "image_bbox": [
    0.2,
    0.13,
    0.72,
    0.22
   ],
   "image_loc": "row of four labelled figures (1)-(4) below the question near top of page",
   "notes": "Image-option MCQ; four shapes labelled (1)-(4). Crop each option to q8_opt0..3.png. Key: option 1."
  },
  {
   "n": 9,
   "type_id": 1,
   "question": "What is 20 minutes before the time shown on the clock?",
   "answer0": "9.15 a.m.",
   "answer1": "9.30 a.m.",
   "answer2": "10.25 a.m.",
   "answer3": "11.05 a.m.",
   "correct_answer": 1,
   "skill_id": 92,
   "difficulty_id": 2,
   "explanation": "The clock shows 9.50 (hour hand near 10, minute hand at 10 -> 50 min). 20 minutes before 9.50 is 9.30.",
   "hints": [
    "Read the time on the clock first.",
    "Subtract 20 minutes from that time."
   ],
   "source": "Ai Tong 2024 P4 End-of-Year Exam Q9",
   "image_needed": true,
   "image_options": false,
   "image_file": "q9.png",
   "image_page": 5,
   "image_bbox": [
    0.52,
    0.3,
    0.72,
    0.44
   ],
   "image_loc": "analogue clock face to the right of the options, upper-middle of page",
   "notes": "Clock reads 9.50. Key: option 2 (9.30 a.m.)."
  },
  {
   "n": 10,
   "type_id": 1,
   "question": "Which of the following is not a net of a cube?",
   "answer0": "Net 1",
   "answer1": "Net 2",
   "answer2": "Net 3",
   "answer3": "Net 4",
   "correct_answer": 0,
   "skill_id": 232,
   "difficulty_id": 2,
   "explanation": "Net (1) cannot be folded into a cube (it has an overlapping/ill-placed face), so it is not a net of a cube; nets (2), (3) and (4) fold into a cube.",
   "hints": [
    "A cube net has exactly 6 squares that fold without overlap.",
    "Mentally fold each net; one of them produces overlapping faces."
   ],
   "source": "Ai Tong 2024 P4 End-of-Year Exam Q10",
   "image_needed": true,
   "image_options": true,
   "image_file": null,
   "image_page": 5,
   "image_bbox": [
    0.16,
    0.63,
    0.7,
    0.85
   ],
   "image_loc": "four candidate nets labelled (1)-(4) arranged in 2x2 in lower half of page",
   "notes": "Image-option MCQ; crop each net to q10_opt0..3.png. The small cube reference figure can be ignored. Key: option 1 (not a net)."
  },
  {
   "n": 11,
   "type_id": 1,
   "question": "Kelly is 7 years old. Her mother is 6 times as old as she is. How old will Kelly be when her mother is 58 years old?",
   "answer0": "16 years old",
   "answer1": "23 years old",
   "answer2": "35 years old",
   "answer3": "42 years old",
   "correct_answer": 1,
   "skill_id": 118,
   "difficulty_id": 2,
   "explanation": "Mother now = 6 x 7 = 42 years. To reach 58 she ages 58 - 42 = 16 years. Kelly also ages 16 years: 7 + 16 = 23 years old.",
   "hints": [
    "Find the mother's current age (6 x 7).",
    "The age gap stays the same as both grow older."
   ],
   "source": "Ai Tong 2024 P4 End-of-Year Exam Q11",
   "image_needed": false,
   "image_options": false,
   "image_file": null,
   "notes": "Key: option 2 (23 years old)."
  },
  {
   "n": 12,
   "type_id": 1,
   "question": "The graph shows the marks scored by 4 girls in a test.<br>Which of the following pie charts best represents the data in the bar graph?",
   "answer0": "Pie chart 1",
   "answer1": "Pie chart 2",
   "answer2": "Pie chart 3",
   "answer3": "Pie chart 4",
   "correct_answer": 1,
   "skill_id": 235,
   "difficulty_id": 3,
   "explanation": "From the bar graph: Betty scored most, then Anna, with Candy and Diana lowest and equal. Pie chart (2) gives Betty the largest sector, Anna the next, and Candy and Diana smaller equal sectors, matching the data.",
   "hints": [
    "Rank the girls by bar height: Betty highest, then Anna, Candy and Diana smallest.",
    "The largest pie sector must be Betty and the two equal small sectors Candy and Diana."
   ],
   "source": "Ai Tong 2024 P4 End-of-Year Exam Q12",
   "image_needed": true,
   "image_options": true,
   "image_file": "q12.png",
   "image_page": 6,
   "image_bbox": [
    0.18,
    0.33,
    0.66,
    0.52
   ],
   "image_loc": "bar graph (Anna/Betty/Candy/Diana) in upper-middle; four option pie charts (1)-(4) below it",
   "notes": "Bar graph is the question figure (q12.png); the four pie charts are the answer options (crop q12_opt0..3.png, pie-chart region approx bbox [0.14,0.60,0.78,0.92] on page 6). Key: option 2."
  },
  {
   "n": 13,
   "type_id": 1,
   "question": "Nick bought 7 bars of chocolate. Each bar of chocolate cost $2.40. He paid for the chocolate with a $50 note. How much change did Nick get?",
   "answer0": "$16.80",
   "answer1": "$33.20",
   "answer2": "$34.80",
   "answer3": "$40.60",
   "correct_answer": 1,
   "skill_id": 131,
   "difficulty_id": 2,
   "explanation": "Cost = 7 x $2.40 = $16.80. Change = $50 - $16.80 = $33.20.",
   "hints": [
    "Find the total cost first (7 x $2.40).",
    "Subtract the total cost from $50."
   ],
   "source": "Ai Tong 2024 P4 End-of-Year Exam Q13",
   "image_needed": false,
   "image_options": false,
   "image_file": null,
   "notes": "Key: option 2 ($33.20)."
  },
  {
   "n": 14,
   "type_id": 1,
   "question": "The perimeter of the rectangle is 48 cm. Its breadth is 8 cm. What is the area of the rectangle?",
   "answer0": "16 cm²",
   "answer1": "64 cm²",
   "answer2": "128 cm²",
   "answer3": "320 cm²",
   "correct_answer": 2,
   "skill_id": 136,
   "difficulty_id": 2,
   "explanation": "Half the perimeter = length + breadth = 48 / 2 = 24 cm. Length = 24 - 8 = 16 cm. Area = 16 x 8 = 128 cm².",
   "hints": [
    "Perimeter = 2 x (length + breadth), so length + breadth = 24 cm.",
    "Length = 24 - 8 = 16 cm; Area = length x breadth."
   ],
   "source": "Ai Tong 2024 P4 End-of-Year Exam Q14",
   "image_needed": true,
   "image_options": false,
   "image_file": "q14.png",
   "image_page": 7,
   "image_bbox": [
    0.3,
    0.31,
    0.58,
    0.41
   ],
   "image_loc": "rectangle labelled 'Perimeter = 48 cm' with '8 cm' on its right side, middle of page",
   "notes": "Key: option 3 (128 cm²)."
  },
  {
   "n": 15,
   "type_id": 1,
   "question": "Mrs Wong had some cupcakes. She gave $$\\frac{1}{4}$$ of the cupcakes to her sister and $$\\frac{5}{12}$$ of them to her neighbours. She gave away 72 cupcakes altogether. How many cupcakes did Mrs Wong have at first?",
   "answer0": "36",
   "answer1": "48",
   "answer2": "108",
   "answer3": "216",
   "correct_answer": 2,
   "skill_id": 122,
   "difficulty_id": 3,
   "explanation": "Fraction given away = 1/4 + 5/12 = 3/12 + 5/12 = 8/12 = 2/3. So 2/3 of the total = 72 -> 1/3 = 36 -> total = 3 x 36 = 108.",
   "hints": [
    "Add the two fractions given away.",
    "If 2/3 = 72, find the whole by working out 1 unit (1/3)."
   ],
   "source": "Ai Tong 2024 P4 End-of-Year Exam Q15",
   "image_needed": false,
   "image_options": false,
   "image_file": null,
   "notes": "Key: option 3 (108)."
  },
  {
   "n": 16,
   "type_id": 2,
   "question": "What is the value of the digit 7 in 74 965? [?]",
   "answer0": "70000",
   "answer1": null,
   "answer2": null,
   "answer3": null,
   "correct_answer": null,
   "skill_id": 105,
   "difficulty_id": 1,
   "explanation": "The 7 is in the ten thousands place, so its value is 70 000.",
   "hints": [
    "Identify the place of the digit 7.",
    "7 ten thousands = 70 000."
   ],
   "source": "Ai Tong 2024 P4 End-of-Year Exam Q16",
   "image_needed": false,
   "image_options": false,
   "image_file": null,
   "notes": "Key: 70000."
  },
  {
   "n": 17,
   "type_id": 2,
   "question": "Find the product of 1370 and 9. [?]",
   "answer0": "12330",
   "answer1": null,
   "answer2": null,
   "answer3": null,
   "correct_answer": null,
   "skill_id": 116,
   "difficulty_id": 1,
   "explanation": "1370 x 9 = 12 330.",
   "hints": [
    "'Product' means multiply.",
    "1370 x 9 = 12 330."
   ],
   "source": "Ai Tong 2024 P4 End-of-Year Exam Q17",
   "image_needed": false,
   "image_options": false,
   "image_file": null,
   "notes": "Key: 12330."
  },
  {
   "n": 18,
   "type_id": 1,
   "question": "In the figure, name the two angles that are smaller than 90°.",
   "answer0": "∠c and ∠e",
   "answer1": "∠a and ∠b",
   "answer2": "∠b and ∠d",
   "answer3": "∠a and ∠d",
   "correct_answer": 0,
   "skill_id": 99,
   "difficulty_id": 2,
   "explanation": "In the quadrilateral, angles c (top-left) and e (bottom-right) are acute (smaller than 90°); the others are 90° or larger.",
   "hints": [
    "An angle smaller than 90° is acute (looks 'sharp').",
    "Compare each marked angle to a right angle."
   ],
   "source": "Ai Tong 2024 P4 End-of-Year Exam Q18",
   "image_needed": true,
   "image_options": false,
   "image_file": "q18.png",
   "image_page": 8,
   "image_bbox": [
    0.2,
    0.58,
    0.5,
    0.8
   ],
   "image_loc": "irregular quadrilateral with marked angles a, b, c, d, e in middle-left of page",
   "notes": "Converted from free-response ('name two angles smaller than 90 deg') to MCQ; answer is angles c and e. Key: angle e and angle c."
  },
  {
   "n": 19,
   "type_id": 2,
   "question": "Write the missing number in the number pattern.<br>2649, 2799, 2949, [?], 3249",
   "answer0": "3099",
   "answer1": null,
   "answer2": null,
   "answer3": null,
   "correct_answer": null,
   "skill_id": 108,
   "difficulty_id": 2,
   "explanation": "The pattern increases by 150 each time: 2949 + 150 = 3099 (and 3099 + 150 = 3249).",
   "hints": [
    "Find the difference between consecutive terms.",
    "Each term is 150 more than the one before."
   ],
   "source": "Ai Tong 2024 P4 End-of-Year Exam Q19",
   "image_needed": false,
   "image_options": false,
   "image_file": null,
   "notes": "Key: 3099."
  },
  {
   "n": 20,
   "type_id": 2,
   "question": "Which two of the fractions below are equivalent to $$\\frac{4}{6}$$? [?] and [?]",
   "answer0": "2/3",
   "answer1": "8/12",
   "answer2": null,
   "answer3": null,
   "correct_answer": null,
   "skill_id": 77,
   "difficulty_id": 2,
   "explanation": "4/6 simplifies to 2/3. Multiplying numerator and denominator by 2 gives 8/12. So 2/3 and 8/12 are equivalent to 4/6.",
   "hints": [
    "Simplify 4/6 by dividing by 2.",
    "Find a fraction equal to it by multiplying top and bottom by the same number."
   ],
   "source": "Ai Tong 2024 P4 End-of-Year Exam Q20",
   "image_needed": false,
   "image_options": false,
   "image_file": null,
   "notes": "Two-blank FIB. Answers as plain a/b for grading. Original question lists a set of fractions to choose from (not legible/listed here); key gives 2/3 and 8/12. notes: original options not shown on rendered page."
  },
  {
   "n": 21,
   "type_id": 2,
   "question": "Write the decimal represented by A. [?]",
   "answer0": "0.38",
   "answer1": null,
   "answer2": null,
   "answer3": null,
   "correct_answer": null,
   "skill_id": 123,
   "difficulty_id": 2,
   "explanation": "The number line from 0.3 to 0.4 is divided into 10 equal parts of 0.01. A is at the 8th mark after 0.3, so A = 0.38.",
   "hints": [
    "Each small interval between 0.3 and 0.4 is 0.01.",
    "Count the marks from 0.3 to A."
   ],
   "source": "Ai Tong 2024 P4 End-of-Year Exam Q21",
   "image_needed": true,
   "image_options": false,
   "image_file": "q21.png",
   "image_page": 9,
   "image_bbox": [
    0.22,
    0.52,
    0.52,
    0.62
   ],
   "image_loc": "number line marked 0.3 and 0.4 with arrow pointing to A, middle of page",
   "notes": "Key: 0.38."
  },
  {
   "n": 22,
   "type_id": 2,
   "question": "Write 4 hundredths as a decimal. [?]",
   "answer0": "0.04",
   "answer1": null,
   "answer2": null,
   "answer3": null,
   "correct_answer": null,
   "skill_id": 123,
   "difficulty_id": 1,
   "explanation": "4 hundredths = 4/100 = 0.04.",
   "hints": [
    "Hundredths is the 2nd decimal place.",
    "4 hundredths = 0.04."
   ],
   "source": "Ai Tong 2024 P4 End-of-Year Exam Q22",
   "image_needed": false,
   "image_options": false,
   "image_file": null,
   "notes": "Key: 0.04."
  },
  {
   "n": 23,
   "type_id": 2,
   "question": "In the figure, ABCD is a square. Find ∠y. [?]",
   "answer0": "53",
   "answer1": null,
   "answer2": null,
   "answer3": null,
   "correct_answer": null,
   "skill_id": 230,
   "difficulty_id": 2,
   "explanation": "Angle ABC of the square is 90°. The diagonal makes a 37° angle, so ∠y = 90° - 37° = 53°.",
   "hints": [
    "Each corner of a square is 90°.",
    "∠y = 90° - 37°."
   ],
   "source": "Ai Tong 2024 P4 End-of-Year Exam Q23",
   "image_needed": true,
   "image_options": false,
   "image_file": "q23.png",
   "image_page": 10,
   "image_bbox": [
    0.3,
    0.15,
    0.54,
    0.32
   ],
   "image_loc": "square ABCD with a line from corner B to a point on DC, angles y and 37 deg marked at B, upper-middle of page",
   "notes": "Answer is 53 (degrees). Key: 90 - 37 = 53 deg."
  },
  {
   "n": 24,
   "type_id": 2,
   "question": "Arrange the following fractions from the greatest to the smallest.<br>$$\\frac{3}{4}$$ , $$\\frac{1}{2}$$ , $$\\frac{5}{8}$$<br>[?] , [?] , [?]",
   "answer0": "3/4",
   "answer1": "5/8",
   "answer2": "1/2",
   "answer3": null,
   "correct_answer": null,
   "skill_id": 79,
   "difficulty_id": 2,
   "explanation": "Convert to eighths: 3/4 = 6/8, 1/2 = 4/8, 5/8 = 5/8. Greatest to smallest: 6/8 > 5/8 > 4/8, i.e. 3/4, 5/8, 1/2.",
   "hints": [
    "Make the denominators the same (eighths).",
    "3/4 = 6/8, 1/2 = 4/8."
   ],
   "source": "Ai Tong 2024 P4 End-of-Year Exam Q24",
   "image_needed": false,
   "image_options": false,
   "image_file": null,
   "notes": "Three-blank FIB in order greatest->smallest. Plain a/b answers. Key: 3/4, 5/8, 1/2."
  },
  {
   "n": 25,
   "type_id": 2,
   "question": "Name the angle that measures 130°. ∠[?]",
   "answer0": "BQE",
   "answer1": null,
   "answer2": null,
   "answer3": null,
   "correct_answer": null,
   "skill_id": 139,
   "difficulty_id": 2,
   "explanation": "On the protractor, ray QE is along the 0° base line and ray QB points to the 130° mark, so the angle measuring 130° is ∠BQE.",
   "hints": [
    "Find the two rays whose readings differ by 130°.",
    "Read from the base line QE up to QB."
   ],
   "source": "Ai Tong 2024 P4 End-of-Year Exam Q25",
   "image_needed": true,
   "image_options": false,
   "image_file": "q25.png",
   "image_page": 10,
   "image_bbox": [
    0.22,
    0.62,
    0.66,
    0.8
   ],
   "image_loc": "protractor with rays to points A, B, C, D, E from centre Q, lower half of page",
   "notes": "Answer is BQE (letter answer accepted by key). Key: angle BQE."
  },
  {
   "n": 26,
   "type_id": 2,
   "question": "Figure X and Y are 2 different geometric figures. Write the letter representing the figure: a) Prism [?]  b) Pyramid [?]",
   "answer0": "Y",
   "answer1": "X",
   "answer2": null,
   "answer3": null,
   "correct_answer": null,
   "skill_id": 231,
   "difficulty_id": 2,
   "explanation": "Figure X comes to a single apex (a pyramid). Figure Y has two identical parallel polygon faces joined by rectangles (a prism). So Prism = Y, Pyramid = X.",
   "hints": [
    "A pyramid has one apex; a prism has two identical parallel ends.",
    "Match each figure to its solid name."
   ],
   "source": "Ai Tong 2024 P4 End-of-Year Exam Q26",
   "image_needed": true,
   "image_options": false,
   "image_file": "q26.png",
   "image_page": 11,
   "image_bbox": [
    0.2,
    0.13,
    0.66,
    0.3
   ],
   "image_loc": "two 3-D solids labelled Figure X (pyramid) and Figure Y (pentagonal prism) near top of page",
   "notes": "Two-blank FIB (letter answers). Key: a) Y (prism), b) X (pyramid)."
  },
  {
   "n": 27,
   "type_id": 2,
   "question": "Hazli bought a box of pencils that cost $4.70. He paid using 7 fifty-cent coins and some twenty-cent coins. How many twenty-cent coins did he use? [?]",
   "answer0": "6",
   "answer1": null,
   "answer2": null,
   "answer3": null,
   "correct_answer": null,
   "skill_id": 131,
   "difficulty_id": 2,
   "explanation": "7 fifty-cent coins = 7 x $0.50 = $3.50. Remaining = $4.70 - $3.50 = $1.20. Number of twenty-cent coins = $1.20 / $0.20 = 6.",
   "hints": [
    "Find the value of the fifty-cent coins first.",
    "Divide the remaining amount by $0.20."
   ],
   "source": "Ai Tong 2024 P4 End-of-Year Exam Q27",
   "image_needed": false,
   "image_options": false,
   "image_file": null,
   "notes": "Key: 0.5x7=3.5; 4.7-3.5=1.2; 1.2/0.2=6."
  },
  {
   "n": 28,
   "type_id": 2,
   "question": "What was the decrease in the number of bicycles sold from Friday to Saturday? [?]",
   "answer0": "8",
   "answer1": null,
   "answer2": null,
   "answer3": null,
   "correct_answer": null,
   "skill_id": 147,
   "difficulty_id": 1,
   "explanation": "From the line graph, Friday = 28 and Saturday = 20. Decrease = 28 - 20 = 8.",
   "hints": [
    "Read the Friday and Saturday values from the graph.",
    "Decrease = Friday value - Saturday value."
   ],
   "source": "Ai Tong 2024 P4 End-of-Year Exam Q28",
   "image_needed": true,
   "image_options": false,
   "image_file": "q28.png",
   "image_page": 12,
   "image_bbox": [
    0.3,
    0.14,
    0.7,
    0.45
   ],
   "image_loc": "line graph of bicycles sold Mon-Sat near top of page (shared by Q28 and Q29)",
   "notes": "Shared line graph (Mon24, Tue18, Wed20, Thu6, Fri28, Sat20). Key: 8. Same figure used for Q29."
  },
  {
   "n": 29,
   "type_id": 1,
   "question": "On which day was the number of bicycles sold four times as many as that sold on Thursday?",
   "answer0": "Monday",
   "answer1": "Tuesday",
   "answer2": "Friday",
   "answer3": "Saturday",
   "correct_answer": 0,
   "skill_id": 147,
   "difficulty_id": 2,
   "explanation": "Thursday = 6 bicycles. 4 x 6 = 24. Monday sold 24 bicycles, so the answer is Monday.",
   "hints": [
    "Read Thursday's value, then multiply by 4.",
    "Find the day whose value equals that product."
   ],
   "source": "Ai Tong 2024 P4 End-of-Year Exam Q29",
   "image_needed": true,
   "image_options": false,
   "image_file": "q29.png",
   "image_page": 12,
   "image_bbox": [
    0.3,
    0.14,
    0.7,
    0.45
   ],
   "image_loc": "line graph of bicycles sold Mon-Sat near top of page (shared with Q28)",
   "notes": "Converted free-response to MCQ. Thu=6, 6x4=24=Monday. Key: 6x4=24, Ans Monday. Uses same shared line graph as Q28."
  },
  {
   "n": 30,
   "type_id": 0,
   "question": "Complete the symmetric figure with the dotted line as the line of symmetry.",
   "answer0": null,
   "answer1": null,
   "answer2": null,
   "answer3": null,
   "correct_answer": null,
   "skill_id": 145,
   "difficulty_id": 2,
   "explanation": "Reflect each vertex of the given half-figure across the vertical dotted line to draw the mirror image, completing the symmetric figure.",
   "hints": [
    "Reflect each point the same distance on the other side of the dotted line.",
    "Join the reflected points to mirror the shape."
   ],
   "source": "Ai Tong 2024 P4 End-of-Year Exam Q30",
   "image_needed": true,
   "image_options": false,
   "image_file": "q30.png",
   "image_page": 13,
   "image_bbox": [
    0.28,
    0.14,
    0.66,
    0.4
   ],
   "image_loc": "square grid with a partial figure and a vertical dotted line of symmetry, upper-middle of page",
   "notes": "Draw/complete-figure task with no value answer -> type_id 0 (skipped on insert). Key shows the completed reflected figure."
  },
  {
   "n": 31,
   "type_id": 2,
   "question": "The weighing scale shows the mass of a tray with 5 identical balls. The mass of the tray is 200 g. What is the mass of each ball? [?]",
   "answer0": "56",
   "answer1": null,
   "answer2": null,
   "answer3": null,
   "correct_answer": null,
   "skill_id": 54,
   "difficulty_id": 2,
   "explanation": "Scale reads 480 g for tray + 5 balls. Mass of 5 balls = 480 - 200 = 280 g. Each ball = 280 / 5 = 56 g.",
   "hints": [
    "Subtract the tray's mass from the total reading.",
    "Divide the balls' total mass by 5."
   ],
   "source": "Ai Tong 2024 P4 End-of-Year Exam Q31",
   "image_needed": true,
   "image_options": false,
   "image_file": "q31.png",
   "image_page": 13,
   "image_bbox": [
    0.16,
    0.52,
    0.42,
    0.78
   ],
   "image_loc": "weighing scale dial with a tray of 5 balls on top, lower-middle of page",
   "notes": "Answer in grams. Scale reads 480 g. Key: 480-200=280; 280/5=56."
  },
  {
   "n": 32,
   "type_id": 2,
   "question": "In the figure, all lines meet at right angles. Find the perimeter of the figure. [?]",
   "answer0": "118",
   "answer1": null,
   "answer2": null,
   "answer3": null,
   "correct_answer": null,
   "skill_id": 138,
   "difficulty_id": 3,
   "explanation": "Top = 16, right-upper = 18, the step-out across = 32 - 16 = 16, the lower-right drop = 9, total down = 18 + 9 = 27, bottom = 32, left side = 27. Perimeter = 16 + 18 + 16 + 9 + 32 + 27 = 118 cm.",
   "hints": [
    "Find the missing side lengths using the right angles.",
    "Opposite horizontal sides total 32; opposite vertical sides total 27."
   ],
   "source": "Ai Tong 2024 P4 End-of-Year Exam Q32",
   "image_needed": true,
   "image_options": false,
   "image_file": "q32.png",
   "image_page": 14,
   "image_bbox": [
    0.28,
    0.16,
    0.6,
    0.34
   ],
   "image_loc": "L-shaped rectilinear figure with sides 16 cm, 18 cm, 9 cm, 32 cm marked, upper-middle of page",
   "notes": "Answer in cm. Key: 18+9+27 ... perimeter = 118 cm (16+18+16+9+32+27)."
  },
  {
   "n": 33,
   "type_id": 2,
   "question": "A group of children took part in a race. $$\\frac{3}{8}$$ of the participants were girls. There were 120 boys. How many girls were there? [?]",
   "answer0": "72",
   "answer1": null,
   "answer2": null,
   "answer3": null,
   "correct_answer": null,
   "skill_id": 122,
   "difficulty_id": 2,
   "explanation": "Girls = 3/8, so boys = 5/8 = 120. 1 unit (1/8) = 120 / 5 = 24. Girls = 3 x 24 = 72.",
   "hints": [
    "If 3/8 are girls, what fraction are boys?",
    "Find 1 unit from the boys, then multiply for the girls."
   ],
   "source": "Ai Tong 2024 P4 End-of-Year Exam Q33",
   "image_needed": false,
   "image_options": false,
   "image_file": null,
   "notes": "Key: 120/5=24; 24x3=72."
  },
  {
   "n": 34,
   "type_id": 1,
   "question": "Thaddeus uses the letters in his name to form the pattern below.<br>THADDEUSTHADDEUST ... ?<br>What is the 65th letter in the pattern?",
   "answer0": "T",
   "answer1": "H",
   "answer2": "S",
   "answer3": "U",
   "correct_answer": 0,
   "skill_id": 108,
   "difficulty_id": 2,
   "explanation": "'THADDEUS' has 8 letters and repeats. 65 / 8 = 8 remainder 1, so the 65th letter is the 1st letter of the block, T.",
   "hints": [
    "The block 'THADDEUS' has 8 letters and repeats.",
    "Divide 65 by 8 and use the remainder to find the position."
   ],
   "source": "Ai Tong 2024 P4 End-of-Year Exam Q34",
   "image_needed": false,
   "image_options": false,
   "image_file": null,
   "notes": "Converted to MCQ (single-letter answer must be MCQ, not FIB). 65 = 8x8 + 1 -> T. Key: 65/8 = 8R1, Ans T."
  },
  {
   "n": 35,
   "type_id": 2,
   "question": "Bob jogged a total of 7.3 km from Monday to Friday. He jogged a total of 4.2 km on the first 3 days. He jogged the same distance on each of the remaining 2 days. What distance did Bob jog on Friday? [?]",
   "answer0": "1.55",
   "answer1": null,
   "answer2": null,
   "answer3": null,
   "correct_answer": null,
   "skill_id": 131,
   "difficulty_id": 2,
   "explanation": "Distance over the last 2 days = 7.3 - 4.2 = 3.1 km. Each of these 2 days is equal, so Friday = 3.1 / 2 = 1.55 km.",
   "hints": [
    "Find the total for the remaining 2 days.",
    "Divide that by 2 since both days are equal."
   ],
   "source": "Ai Tong 2024 P4 End-of-Year Exam Q35",
   "image_needed": false,
   "image_options": false,
   "image_file": null,
   "notes": "Answer in km. Key: 7.3-4.2=3.1; 3.1/2=1.55."
  },
  {
   "n": 36,
   "type_id": 2,
   "question": "Box A, B and C are placed on a weighing balance. Box A has a mass of 44.5 kg. Box B is 31.6 kg heavier than Box A. What is the mass of Box C? [?]",
   "answer0": "120.6",
   "answer1": null,
   "answer2": null,
   "answer3": null,
   "correct_answer": null,
   "skill_id": 131,
   "difficulty_id": 2,
   "explanation": "Box B = 44.5 + 31.6 = 76.1 kg. The balance shows A and B together balance C, so Box C = 44.5 + 76.1 = 120.6 kg.",
   "hints": [
    "Find Box B's mass first.",
    "On a balance, Box C equals the combined mass of A and B."
   ],
   "source": "Ai Tong 2024 P4 End-of-Year Exam Q36",
   "image_needed": true,
   "image_options": false,
   "image_file": "q36.png",
   "image_page": 16,
   "image_bbox": [
    0.22,
    0.28,
    0.56,
    0.38
   ],
   "image_loc": "see-saw balance with boxes A and B on the left pan and box C on the right pan, upper-middle of page",
   "notes": "Answer in kg. Key: 44.5+31.6=76.1; 76.1+44.5=120.6."
  },
  {
   "n": 37,
   "type_id": 2,
   "question": "A square piece of paper ABCD is folded at a corner as shown. ∠ECF = 26°. Find ∠x. [?]",
   "answer0": "38",
   "answer1": null,
   "answer2": null,
   "answer3": null,
   "correct_answer": null,
   "skill_id": 230,
   "difficulty_id": 3,
   "explanation": "Corner C of the square is 90°. The fold makes ∠ECF = ∠x's partner equal, so ∠ECF + ∠FCB(=x by folding) ... 26° + 26° = 52° used, leaving ∠x = 90° - 52° = 38°.",
   "hints": [
    "Angle DCB of the square is 90°.",
    "Folding makes two equal 26° angles; subtract their sum from 90°."
   ],
   "source": "Ai Tong 2024 P4 End-of-Year Exam Q37",
   "image_needed": true,
   "image_options": false,
   "image_file": "q37.png",
   "image_page": 17,
   "image_bbox": [
    0.26,
    0.13,
    0.5,
    0.3
   ],
   "image_loc": "square ABCD with corner folded to point F, angles 26 deg and x marked near corner C, upper part of page",
   "notes": "Answer in degrees. Key: 26+26=52; 90-52=38 deg."
  },
  {
   "n": 38,
   "type_id": 2,
   "question": "Jerry had 5 kg of rice. He used $$\\frac{3}{4}$$ kg of it to prepare fried rice and another $$\\frac{1}{6}$$ kg of it to prepare chicken rice.<br>(a) How much rice did Jerry use altogether? [?]<br>(b) How much rice did Jerry have left? Give your answer as a mixed number in its simplest form. [?]",
   "answer0": "11/12",
   "answer1": "4 1/12",
   "answer2": null,
   "answer3": null,
   "correct_answer": null,
   "skill_id": 122,
   "difficulty_id": 3,
   "explanation": "(a) 3/4 + 1/6 = 9/12 + 2/12 = 11/12 kg. (b) Left = 5 - 11/12 = 4 12/12 - 11/12 = 4 1/12 kg.",
   "hints": [
    "(a) Use a common denominator of 12 to add the fractions.",
    "(b) Subtract the amount used from 5 kg; write as a mixed number."
   ],
   "source": "Ai Tong 2024 P4 End-of-Year Exam Q38",
   "image_needed": false,
   "image_options": false,
   "image_file": null,
   "notes": "Two-part FIB. (a) 11/12 kg, (b) 4 1/12 kg. Plain fraction answers for grading. Key: a) 11/12 kg; b) 4 1/12."
  },
  {
   "n": 39,
   "type_id": 2,
   "question": "Devi and Hassan went shopping with the same amount of money. After Devi spent $180 and Hassan spent $78, Hassan had three times the amount of money left as Devi.<br>(a) How much more money did Devi spend than Hassan? [?]<br>(b) How much money did Devi go shopping with? [?]",
   "answer0": "102",
   "answer1": "231",
   "answer2": null,
   "answer3": null,
   "correct_answer": null,
   "skill_id": 118,
   "difficulty_id": 3,
   "explanation": "(a) Devi spent $180 - $78 = $102 more than Hassan. (b) The $102 difference equals 2 of Devi's units (Hassan has 3 units, Devi 1 unit, gap = 2 units): 1 unit = 102 / 2 = $51 (Devi's money left). Devi started with $51 + $180 = $231.",
   "hints": [
    "(a) Subtract Hassan's spending from Devi's.",
    "(b) The extra $102 = 2 units; find Devi's money left, then add what she spent."
   ],
   "source": "Ai Tong 2024 P4 End-of-Year Exam Q39",
   "image_needed": false,
   "image_options": false,
   "image_file": null,
   "notes": "Two-part FIB ($ answers). (a) $102, (b) $231. Key: a) 180-78=102; b) 102/2=51; 51+180=231."
  },
  {
   "n": 40,
   "type_id": 2,
   "question": "The figure is made up of 7 identical rectangles. The length of each rectangle is 10 cm.<br>(a) Find the breadth of each rectangle. [?]<br>(b) Find the area of the figure. [?]",
   "answer0": "4",
   "answer1": "280",
   "answer2": null,
   "answer3": null,
   "correct_answer": null,
   "skill_id": 138,
   "difficulty_id": 3,
   "explanation": "(a) In the top row, 5 breadths span the same width as 2 lengths of the bottom row: 5 x breadth = 2 x 10 = 20, so breadth = 20 / 5 = 4 cm. (b) Area of one rectangle = 10 x 4 = 40 cm². Figure = 7 x 40 = 280 cm².",
   "hints": [
    "Top row of standing rectangles spans the same width as the 2 lying rectangles.",
    "Area of figure = 7 x area of one rectangle."
   ],
   "source": "Ai Tong 2024 P4 End-of-Year Exam Q40",
   "image_needed": true,
   "image_options": false,
   "image_file": "q40.png",
   "image_page": 20,
   "image_bbox": [
    0.18,
    0.15,
    0.5,
    0.28
   ],
   "image_loc": "figure of 7 rectangles (5 standing on top, 2 lying below) with 10 cm marked and breadth '?', upper-left of page",
   "notes": "Two-part FIB. (a) 4 cm, (b) 280 cm². Key: a) 20/5=4 cm; b) 20x14=280 cm² (=7x40)."
  },
  {
   "n": 41,
   "type_id": 2,
   "question": "Vincent mixed 6.4 $$l$$ of blue paint with 7 $$l$$ of white paint. After he poured some of the paint into 1 large and 1 small empty tin, there was 2.15 $$l$$ of paint left. The volume of a large tin was five times as much as a small tin.<br>(a) How much paint did he mix altogether? [?]<br>(b) How much paint was there in the small tin? Give your answer correct to 1 decimal place. [?]",
   "answer0": "13.4",
   "answer1": "1.9",
   "answer2": null,
   "answer3": null,
   "correct_answer": null,
   "skill_id": 131,
   "difficulty_id": 3,
   "explanation": "(a) 6.4 + 7 = 13.4 l. (b) Paint poured into tins = 13.4 - 2.15 = 11.25 l. Large + small = 5 units + 1 unit = 6 units = 11.25 l. Small tin = 11.25 / 6 = 1.875 l ≈ 1.9 l.",
   "hints": [
    "(a) Add the two paint amounts.",
    "(b) Subtract the leftover, then split into 6 equal units (small = 1 unit)."
   ],
   "source": "Ai Tong 2024 P4 End-of-Year Exam Q41",
   "image_needed": false,
   "image_options": false,
   "image_file": null,
   "notes": "Two-part FIB (litres). (a) 13.4 l, (b) 1.9 l (1.875 rounded to 1 dp). Key: a) 7.0+6.4=13.4; b) 11.25/6=1.875 ~ 1.9 litre."
  },
  {
   "n": 42,
   "type_id": 2,
   "question": "The pie chart shows the number of animals at a farm. There were 168 animals altogether. Half of the animals at the farm were cows.<br>(a) How many sheep were there in the farm? [?]<br>(b) What fraction of the animals in the farm were horses? Express your answer in the simplest form. [?]",
   "answer0": "42",
   "answer1": "3/28",
   "answer2": null,
   "answer3": null,
   "correct_answer": null,
   "skill_id": 236,
   "difficulty_id": 3,
   "explanation": "(a) Cows = 1/2. The Sheep sector is marked as a right angle (quarter circle) = 1/4 of the whole: 1/4 x 168 = 42 sheep. (b) Ducks = 1/7. Horses = 1 - 1/2 - 1/4 - 1/7 = 14/28 - 7/28 - 4/28 = 3/28.",
   "hints": [
    "(a) The right-angle mark shows the Sheep sector is 1/4 of the circle.",
    "(b) Subtract the cows, sheep and ducks fractions from 1 whole."
   ],
   "source": "Ai Tong 2024 P4 End-of-Year Exam Q42",
   "image_needed": true,
   "image_options": false,
   "image_file": "q42.png",
   "image_page": 22,
   "image_bbox": [
    0.34,
    0.15,
    0.64,
    0.4
   ],
   "image_loc": "pie chart titled 'Animals at a farm' with sectors Cows, Sheep, Horses, Ducks (1/7), right angle marked, upper-middle of page",
   "notes": "Two-part FIB. (a) 42 sheep, (b) 3/28 (plain fraction). Key: a) 168/4=42; b) 1/2+1/4+1/7 -> horses 3/28."
  },
  {
   "n": 43,
   "type_id": 2,
   "question": "A shop sells T-shirts. Plain T-shirts are sold in packs of 3 (3 for $8) and printed T-shirts are sold in packs of 2 (2 for $8.55).<br>(a) John had some money. He bought 6 printed T-shirts and had no money left. How much money did he have at first? [?]<br>(b) Mei had the same amount of money as John at first. What was the most number of plain T-shirts she could buy? [?]",
   "answer0": "25.65",
   "answer1": "9",
   "answer2": null,
   "answer3": null,
   "correct_answer": null,
   "skill_id": 131,
   "difficulty_id": 3,
   "explanation": "(a) 6 printed = 3 packs of 2. 3 x $8.55 = $25.65, so John had $25.65. (b) Plain at $8 per 3: $25.65 / $8 = 3 packs ($24) with $1.65 left over. 3 packs x 3 = 9 plain T-shirts.",
   "hints": [
    "(a) 6 printed T-shirts = 3 packs of 2 at $8.55 each.",
    "(b) See how many $8 packs of 3 fit into $25.65, then multiply by 3."
   ],
   "source": "Ai Tong 2024 P4 End-of-Year Exam Q43",
   "image_needed": true,
   "image_options": false,
   "image_file": "q43.png",
   "image_page": 23,
   "image_bbox": [
    0.2,
    0.12,
    0.74,
    0.28
   ],
   "image_loc": "two boxes: printed T-shirts (2 for $8.55) and plain T-shirts (3 for $8), upper part of page",
   "notes": "Two-part FIB. (a) $25.65, (b) 9 plain T-shirts. Key: a) 8.55x3=25.65; b) 8x3=24, 3x3=9."
  }
 ]
}