A class consists of students whose average weight is 65.5. Four students of 72.2 kg, 70.3 kg, 67.7 kg and 70.8 kg, joined the class and the average weight increased by 500 gms. Find the number of students initially.
C
Correct answer
Explanation
The correct answer is C because let n be the initial number of students. Total initial weight = 65.5n. Four students join with weights 72.2 + 70.3 + 67.7 + 70.8 = 281 kg. New average = 65.5 + 0.5 = 66 kg for (n + 4) students. Equation: (65.5n + 281)/(n + 4) = 66. Solving: 65.5n + 281 = 66n + 264, so 0.5n = 17, giving n = 34.