Three year ago, the average age of a family of five members was 27 yr. The present average age is also 27 yr after the inclusion of a child into the family. Find the age of the child.
Correct Answer: 12 yr
Explanation:
Total age of 5 memeber (3 yr ago) = 27 x 5 = 135 yr
Total age of 5 members (at present) = 135 + 5 x 3 = 150 yr.
Let the persent age of child = x
∴ 27 = (150 + x)/6
⇒ x = 162 - 150 = 12 yr.
