Question

Question!

The average age of four children is 11 years if the age of three children are 9 years 12 years and 10 years find the age of fourth child?

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Answer 1

Answer:

solution:-

let the age of 4th child be x.

$\bold{average = sum \: of \: all \: outcomes \: no. \: of \: outcomes}$

$\bold{ = 9 + 12 + 10 + \frac{x}{4} = 11}$

$\bold{ = 31 + \frac{x}{4} = 11}$

$\bold{ = 31 + x = 11}$

$\bold{ = 11 \times 4 = 44}$

$\bold{ \implies \: x = 44 - 31}$

$\bold{ \implies \: x = 13}$

Hence,

Age of fourth child is 13.

Answer 2

Given :

• The average age of four children is 11 years.
• the age of three children are 9 years 12 years and 10 years.

To Find :

• Find the age of fourth child ?

Solution :

• Let us assume :

➣ The age of fourth child be x.

We know that,

• Average age = Sum of ages/Number of children

We have :

• Average age = 11 years
• Some of ages = 9 + 12 + 10 + x = (31 + x) years
• Number of childrens = 4

Finding the age of fourth child :

➣ 11 = (31 + x)/4

• Cross multiplication.

➣ 4(11) = 31 + x

➣ 44 = 31 + x

➣ 44 - 31 = x

➣ 13 = x

➣ x = 13

Hence,

• The age of fourth child is 13 years.