The average weight of 30 boys sitting in a bus had some value. A new person added to them whose weight was 40 kg only. Due to his arrival, the average weight of all the boys decreased by 2 kg. Find the average weight of first 30 boys? Choose the most appropriate option
A) 150  B) 122  C) 30  D) 120  E) 102

Rationale: 30 x + 40 = 31 ( x â € “ 2 ) x = 102 e
Answer: E