Question

The average age of 3 sisters is 18 years. If the average age of first 2 sister is 23 years. Find the age of third sister​

Answer 1

Answer:

8 year

Step-by-step explanation:

Let their ages be A, B and C.

Average of their ages is 18 :

⇒ (A + B + C)/3 = 18

⇒ A + B + C = 18*3 = 54     ...(1)

As well as, average age of first 2 sister is 23.

⇒ (A + B)/2 = 23

⇒ A + B = 23*2 = 46         ...(2)

Subtract (2) from (1):

A + B + C = 54

-A - B        = -46

            C = 8  

 Age of the third sister is 8 year

Answer 2

Required answer:-

Question:

• The average age of 3 sisters is 18 years. If the average age of first 2 sister is 23 years. Find the age of third sister.

Solution:

Given,

• Average age of 3 sisters = 18 years

• Average age of first 2 sisters = 23 years

To find:

• Age of third sister

Let,

• Their ages be A , B , C

Step by step explaination:

First we have to calculate value of ( A + B + C ) as their average age 18

So, it will be:

( A + B + C ) / 3 = 18

( A + B + C ) = 18×3

A + B + C = 54 ...(i)

Now, we have to calculate average age of (A+B)

as their average age of first 2 sisters is 23

So, it will be

( A + B ) / 2 = 23

( A + B ) = 23×2

( A + B ) = 46 ...(i)

Now, subtract (ii) from (i)

So it will be:

A + B + C = 54

- A - B. = - 46

C = 8

Therefore age of third sister is 8 years