The average weight of 60 students in a class is 56.4 kg. If 12 students having average weight 59.5 kg leave the class and 15 students having average weight 54 kg join the class, then what is the average weight (in kg) of the students in the class (correct to one decimal place)?

55.2

Sum of weight of 60 students = 60 × 56.4 = 3384 kg

12 students leave the class , Sum of weight of 12 students = 12 × 59.5 = 714 kg

15 students join the class , Sum of weight of 15 students = 15 × 54 = 810 kg

Increment in weight = 810 - 714 = 96 kg

New average of 64 students = \(\frac{3384 + 96}{63}\) = \(\frac{3480}{63}\)

= 55.2 kg