The average age of an adult class is 40years. 8 new students with an avg age of 32years join the class. Therefore decreasing the average by 4year. Find what was theoriginal strength of class?  Pick.
A) 8
B) 12
C) 15
D) 17
E) 18

Rationale: "let original strength = y then , 40 y + 8 x 32 = ( y + 8 ) x 36 â ‡ ’ 40 y + 256 = 36 y + 288 â ‡ ’ 4 y = 32 â ˆ ´ y = 8 a"
Answer: A