Four years ago, the average age of A and B was 20 years. Today, the average age of A, B and C is 25 years. What will be the age of C after 7 years?
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → 34 years
An average of ages gives the sum of the ages, and each person grows 1 year older every year, so a sum of two ages rises by 2 each year.
Sum of the ages of A and B four years ago \(=2\times20=40\) years
Sum of their ages today \(=40+2\times4=48\) years
Sum of the ages of A, B and C today \(=3\times25=75\) years
Age of C today \(=75-48=27\) years
Age of C after 7 years \(=27+7=34\) years
C will be 34 years old after 7 years.