Three years ago, the average age of a family of 5 members was 17 years. A baby was born, but the average age of the family is still the same today. The present age of the baby is ________ :

A3 years

B4 years

C2 years ✓ Correct

D5 years

Correct answer: (C) 2 years

Explanation

The baby is 2 years old now.

Three years ago 5 members averaged 17, so their total was 5 x 17 = 85.

Today those 5 have aged 3 years each : total = 85 + 5 x 3 = 100.

With the baby, 6 members still average 17, so total = 6 x 17 = 102.

Baby's age = 102 - 100 = 2 years.

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