A) 57
B) 58
C) 59
D) 60
Let the average weight of the 59 students be X. Therefore, the total weight of the 59 of them will be 59X.
The question states that when the weight of this student who left is added, the total weight of the class = 59X + 45.
When this student is also included, the average weight decreases by 0.2 kgs.
59X + 45/ 60 = X – 0.2
=> 59X + 45 = 60X – 12
=> 45 + 12 = 60X – 59A
=> X = 57.