The average weight of a certain number of students in a group is 72kg. If 10 students having an average weight 78kg leave and 4 students having an average weight of 80kg join the group, the average weight of students in the group decreases by 0.7kg. The number of students initially in the group are ?
Show answer & explanation
Correct answer: B
Explanation
The correct naswer is option 2 ie 46.
= 72 → (-10) → × (+6)
= 78
+ 6
(-60+32)/n = -0.7
n = 40
= n - 4 + 10
= 40 - 4 + 10 = 46