The average weight of 8 students in a class is y kg. Two new students join the class with a total weight of 60 kg, and the average weight of the class decreases by y/10 kg. If the heavier student among the two new students weighs y − 20 kg, find the difference between the weights of the two new students.

ATQ, The average weight of 8 students is y kg. So, total weight of 8 students = 8y kg. Two new students join the class with a total weight of 60 kg. So, total weight after two students join = 8y + 60. Now, total number of students = 8 + 2 = 10. The average weight decreases by y/10 kg. So, new average weight = y − y/10 New average weight = 10y/10 − y/10 New average weight = 9y/10 Now, total weight of 10 students can also be written as: New average × Number of students Total weight of 10 students = 9y/10 × 10 Total weight of 10 students = 9y. So, 9y = 8y + 60 9y − 8y = 60 y = 60 Now, the heavier student’s weight = y − 20 Heavier student’s weight = 60 − 20 = 40 kg. Total weight of the two new students = 60 kg. So, lighter student’s weight = 60 − 40 = 20 kg. Required difference = 40 − 20 = 20 kg.