3 Years ago, the average of a family of 5 members was

Hi All,

This question is based on the Average Formula, but can actually be solved in a number of different ways (depending on how you choose to set up the 'math'). Here's a solution that focuses on doing the straight-forward 'math':

We're told that 3 YEARS AGO, the average age of a family of 5 members was 17 years.

This means that the SUM of their ages was (5)(17) = 85 years.

A baby was born (meaning that there are now 6 family members). We're told that the PRESENT average age of the family members is the SAME.

This means that the sum of the ages is (6)(17) = 102 years.

We're asked for the PRESENT age of the baby.

Since each of the original 5 family members has aged 3 years since the initial average was calculated, the sum of their PRESENT ages is...

85 + (5)(3) = 100.

Since the current sum of the 6 family members is 102, the baby is 102-100 = 2 years old.

Final Answer:

GMAT assassins aren't born, they're made,
Rich