Let n be the number of items in the dataset.<br><br>
True total = 50 × n.<br>
Reported total = 50n − 83 + 63 = 50n − 20.<br><br>
Reported average = (50n − 20) ÷ n = 49.6.<br>
50n − 20 = 49.6n.<br>
50n − 49.6n = 20.<br>
0.4n = 20, so n = 50.<br><br>
Final Answer: 50