Three years ago, the average age of a family of five members was 17 years. A baby has since been born, and the average age of the family is the same today. What is the age of the baby?
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → 2 years
The total age = average \(\times\) number of members. In 3 years each of the five old members adds 3 years to the total; whatever is left over is the baby's age.
Total age of 5 members three years ago \(=5\times17=85\) years
Their total age today \(=85+5\times3=100\) years
Total age of 6 members today \(=6\times17=102\) years
Age of the baby \(=102-100=2\) years