Question

Three years ago the average age of a family of 5 members was 27 years. On addition of a child to the family, the present average age of the family is still 27 years. Find out the present age of the child.

• A. 16 years
• B. 12 years
• C. 24 years
• D. 20 years
• E. None of these

Answer 1

The correct option is B 12 years

Present average age of 5 members $=27+3=30years$
Sum of present ager of 5 members $=30\times 5=150years$
Let, the present age of the child be x years.
Present average age of 6 members.
$=\frac{150+x}{6}$ and this is equal to 27 years.
So, $\frac{150+x}{6}=27$
or, $x=278\times 6-150$ or, $x=12years$.