Question

The average age of a family of 5 members at the time of the birth of the youngest member was 25 years if now the average age of the family is 28 years, then what is the present age of the youngest member of the family
O 7 years
O 9 years
O 3 years
O 5 years​

Answer 1

Answer:

${3}^{rd} option \: \: \: 3 \: years.$

Step-by-step explanation:

Let the present age of the youngest member be x years.

At the time of birth, average age = 25 years.

Therefore, sum of the ages of 5 members = 25 × 5 = 125.

After x years, sum of the ages of the 5 members = 125 + 4x + x

Average =

$\frac{125 \: + 5x}{5} = 28$

=$125 + 5x \: = 140$

=

$5x \: = 140 - 125$

=

$5x \: = \: 15$

=

$x \: = \: 3$

Hence, third option 3 years is correct.

Answer 2

Given :

The average age of a family of 5 members at the time of the birth of the youngest member was 25 years.

Average age of family now is 28 years.

To find :

The present age of the youngest member of the family.

Solution

Let the present age of youngest member of the family is x years.

The average of family of 5 members at the time of birth of youngest member of a family =

sum of ages of family members at the time of youngest member of a family / 5 = 25 years.

Therefore sum of ages of family members at the time of birth of the youngest member of a family = 5 x 25

= 125 years

Average of present ages of family of 5 members =

sum of present ages of family members / 5 = 28

Therefore sum of present ages of family members =

( 125 + 4x + x ) / 5 = 28

125 + 5x = 5 x 28

125 + 5x =140

5x = 140 - 125

5x = 15

x = 15 / 5

x = 3 years.

Hence present age of youngest member of the family is 3 years.

option (3) .