43. The average age of an adult class is 40 years. Twelve new students with an average age of 32 years join the class, thereby decreasing the average of the class by 4 years. The original strength of the class was.
A.10 B.12
C.11 D.15
Answer: 12
Explanation: Let, original strength = x.
40x + 12*32 / (x + 12) = 36 or x = 12
