The average weight of some persons in a club was 80kg. Seven persons with average weight 85.2kg joined the club and at the same time 2 persons with the average weight 72.7 KG left the club. The average weight of all the persons in the group increased by 1.02 Kg. How many people were there initially in the club?
Show answer & explanation
Correct answer: B
Explanation
The correct answer is option 2 i.e. 45.
Total initial weight = 80x
Weight added = 7 × 85.2 = 596.4 kg
Weight removed = 2 × 72.7 = 145.4 kg
So, net added = 596.4 − 145.4 = 451 kg
Number of people after change = x + 7 − 2 = x + 5
New average = 80+1.02=81.02
Total weight after change = 81.02(x+5)
New total weight = Old total weight + Net added
⇒ 81.02(x+5) = 80x + 451
⇒ 81.02x − 80x = 451 − 405.1 ⇒ 1.02x = 45.9 ⇒ x = 45.9/1.02 = 45