### The average age of four boys A, B, C and D is 5 years and the average age A, B, D, E is 6 years. C is 8 years old. The age of E is (in years) :

A. 12

B. 13

C. 14

D. 15

$\begin{array}{l}\text{According to the question,}\\ \frac{A+B+C+D}{4}=5\\ A+B+C+D=20\ldots..(i)\\ \frac{A+B+D+E}{4}=6\\ A+B+D+E=24\ldots..(ii)\end{array}$ If C = 8 years old, put the value of ‘C’ in equation (i) $\begin{array}{l}\text{∴ A + B + D + 8 = 20}\\ \text{A + B + D = 12…..(iii)}\end{array}$ Put the value of equation (iii) in equation (ii) $\begin{array}{l}\text{12 + E = 24}\\ \text{E = 24 – 12}\\ \text{∴ E = 12}\end{array}$