Three years ago, the average age of a family of 5 members was 17 years. A baby having been born and the average age of the family is the same as three years ago. The present age of the baby (in years) is _____?

Three years ago, the average age of a family of 5 members was 17 years. A baby having been born and the average age of the family is the same as three years ago. The present age of the baby (in years) is _____?

Explanation

Three years ago, the total age of the 5 family members was:

5 x 17 = 85 years

Now, the total age of the 5 family members, considering the 3 years that have passed, is:

85 + 5 x 3 = 100 years

The total age of the 6 family members (including the baby) is:

100 + baby's age

Since the average age remains the same (17 years), we can set up the equation:

(100 + baby's age) / 6 = 17

Multiply both sides by 6:

100 + baby's age = 102

Subtract 100 from both sides:

baby's age = 2