The avg age of an adult class is 40years. 12new students with an avg age of 32years join the class. Therefore decreasingthe avg by 4year. Find what was the original strength of class?  Choose the correct choice from the following:  A) 8  B) 12  C) 15  D) 16  E) 19

Rationale: let original strength = y then , 40 y + 12 x 32 = ( y + 12 ) x 36 ⇒ 40 y + 384 = 36 y + 432 ⇒ 4 y = 48 ∴ y = 12 b
Answer: B