Question

The average age of 10 children is 8 years 2 month.If the average age of 9 children is 6 year 2 month.find the average age of 10 th child?

Answer 1

$average = \frac{sum \: of \: observations}{total \: no \: of \: observations}$
8years 2 months = 8(12)+2
= 96+2

= 98 months

$98 = \frac{sum}{10} \\ \\ 980 = sum \: of \: 10 \: children$
Similarly

$74 = \frac{sum \: of \: ages \: of \: 9 \: children}{9} \\ \\ sum = 666$
age of 10th child= sum of 10children - sum of 9 children
=980-666
= 314 months

that is equal to 26 years and two months

Answer 2

Step-by-step explanation:

average = \frac{sum \: of \: observations}{total \: no \: of \: observations}average=

totalnoofobservations

sumofobservations

8years 2 months = 8(12)+2

= 96+2

= 98 months

\begin{lgathered}98 = \frac{sum}{10} \\ \\ 980 = sum \: of \: 10 \: children\end{lgathered}

98=

10

sum

980=sumof10children

Similarly

\begin{lgathered}74 = \frac{sum \: of \: ages \: of \: 9 \: children}{9} \\ \\ sum = 666\end{lgathered}

74=

9

sumofagesof9children

sum=666

age of 10th child= sum of 10children - sum of 9 children

=980-666

= 314 months

that is equal to 26 years and two months