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

Answer:

12

Step-by-step 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