The average weight of 56 students in a group is 55 kg. If 12 students of average weight 60 kg leave and 6 students of average weight 52.5 kg join the group, then the average weight of the remaining students in the group decreases by:
Show answer & explanation
Correct answer: C
Explanation
The correct answer is option 3 i.e. 1.5 kg.
Given:
The average weight of 56 students in a group is 55 kg
If 12 students of average weight 60 kg leave and 6 students of average weight 52.5 kg join the group
Formula used:
Average = Sum of observation/number of observation ----- (1)
Calculations:
Using equation (1), we get
Total weight of class = 55 × 56 = 3080
Weight of 12 students who left the group = 12 × 60 = 720
Weight of 6 students who joined the group = 52.5 × 6 = 315
Total students of class = 3080 - 720 + 315 = 2675
Number of students left in the class = 56 - 12 + 6 = 50
Required new average weight = 2675/50 = 53.5
Average weight decreased = 55 - 53.5 = 1.5 kg