The average score of a class of boys and girls in an examination is A. The ratio of boys and girls in the class is 3 : 1. If the average score of the boys is A + 1, the average score of the girls is-

A. A – 1 B. A – 3 C. A + 1 D. A + 3 Answer: Option B

Solution(By Apex Team)

Let the number of boys and girls in the class be 3x and x respectively. Let the average score of the girls be y. Then, $\begin{array}{l}\text{⇒ 3x (A + 1) + xy = (3x + x) A}\\ \text{⇒ 3 (A + 1) y = 4A}\\ \text{⇒ y = A – 3}\end{array}$

A. 20
B. 21
C. 28
D. 32

A. 18
B. 20
C. 24
D. 30

A. 10 years
B. 10.5 years
C. 11 years
D. 12 years