Question

Average age of a family of 4 members was 19 years, 4 years back. Birth of a new child kept the average age of the family same even today. How old is the child today?

Answer 1

it helps you the answer is 7 years old

Answer 2

Answer:

3 years.

Step-by-step explanation:

Average age of a family of 4 members was 19 years, 4 years back.

Let the ages of 4 members be a,b,c,d 4 years ago

$19 = \frac{\text{Sum of all ages}}{4}$

$19 = \frac{a+b+c+d}{4}$

$19 \times 4 = \text{a+b+c+d}$

$76 = \text{a+b+c+d}$

So, the sum of ages of 4 members 4 years ago is 76

Now after four years their ages will be increase by 4

So, the sum of ages of 4 members after 4 years = a+4+b+4+c+4+d+4

                                                                                =a+b+c+d+16

                                                                                = 76+16

                                                                                = 92

Let the present age of baby be x

Sum of ages of 4 members and baby = 92+x

Now total members = 4+1=5

the average age of the family same even today.

So, $19 = \frac{92+x}{5}$

$19 \times 5 =92+x$

$95 =92+x$                

$x=3$    

Hence The present age of child is 3 years.