Question

4. Complete the chart.
JUJLY
Military Organisation
Cavalry
Havaldar


please tell the answer ​

Answer 1

Explanation:

Answer:

Let the sum of of Ages of 5 boys be = y

ACCORDING TO THE QUESTION

avg.of their ages is 13yrs.

i.e.

\begin{gathered}avg. = \dfrac{sum \: of \: their \: ages}{no \: of \: boys} \\ \\ 13 = \frac{y}{5} \\ \\ y = 13 \times 5 \\ \\ \blue{\Large \boxed{{\boxed{y= 65yrs}}}} \\ \\ \end{gathered}

avg.=

noofboys

sumoftheirages

13=

5

y

y=13×5

y=65yrs

Now

Let

age of 6th boy be = x

Now New avg. becomes 12yrs

i.e.

\begin{gathered} \dfrac{y + x}{6} = 12 \\ \\ y + x = 72 \\ \\ 65 + x = 72 \\ \\ x =72 - 65 \\ \\ \blue{\Large{ \boxed {\boxed{\boxed{\boxed{x = 7yrs}}}}}}\end{gathered}

6

y+x

=12

y+x=72

65+x=72

x=72−65

x=7yrs

So age of 6th boy is 7yrs .

Hence option D is correct