2 वर्ष पूर्व परिवार की औसत आयु 18 वर्ष थी, जिसमे 8 सदस्य थे। एक बच्चे के सम्मीलित हो जाने के बाद, परिवार की वर्तमान औसत आयु सामान है। बच्चे की वर्तमान आयु ज्ञात करे?

Options

A. 2 years
B. `1(1)/(2)` years
C. 1 years
D. `2(1)/(2)` years

Answer

A

Explanation

According to the question
Average age of 8 members two years ago =18 years
Sum of age of 8 members two years ago =144 years
After the addition of a baby the average age of the family is same today.
i.e., Average age of 9 members today = 18 years
Sum of age of 9 members today =162 years
In these 2 years the age of 8 members is also increased .
Increase in the age of 8 members = 8 x 2 =16 years
`therefore` Sum of ages of 8 members today =144+16=160 years
`therefore` Age of child =162-160
=2 years