Question

Harpreet, Sukhpreet and Komalpreet are three sisters. Sukhpreet is x years old. Harpreet is 3 years older than Sukhpreet. Komalpreet is twice the age of Harpreet. If the average age of the three sisters is 15, how old is Harpreet?

Answer 1

12

Explanation:

Givens

Harpreet = x + 3

Sukhpreet = x

Komalpreet = 2*(x + 3)

Average Age = 15

Equation

[(x + 3) + x + 2*(x + 3) ] / 3 = 15 Multiply both sides by 3

Solution

3 [(x + 3) + x + 2*(x + 3) ] / 3 = 15 * 3 Combine

[(x + 3) + x + 2*(x + 3) ] = 45 Remove the brackets

x + 3 + x + 2x + 6 = 45 Combine like terms

4x + 9 = 45 Subtract 9 from both sides

4x + 9 - 9 = 45 - 9 Combine

4x = 36 Divide by 4

4x/4 = 36/4

x = 9

Answer

Harpreet is x+ 3 = 9 + 3 = 12