The average weight of some person in a group is 76 kg. If 15 persons with an average weight of 72 kg join the group of 5 persons with an average weight of 84 kg leave the group, the average weight of the persons in the group in both cases is the same. How many persons were there in the group, initially?
Show answer & explanation
Correct answer: B
Explanation
The correct answer is option 2 i.e. 45.
Let the total number of persons = x
So, [15(76 - 72)]/(x + 15) = [5(84 - 76)]/(x - 5)
⇒ 60/(x + 15) = 40/(x - 5)
⇒ 3/(x + 15) = 2/(x - 5)
⇒ 3x - 15 = 2x + 30
⇒ x = 45