Question

The mean of the given data is $30$. If total data is $70$, then missing numbers are

• A. $14$, $23$
• B. $25$, $21$
• C. $24$, $13$
• D. $40$, $31$

Answer 1

Answer: (A)

$14$, $23$

Answer 2

We have, Also, $\Sigma f = 70$, $\Sigma f x = 25f_{1}+45f_{2}+715$ $\Rightarrow 8 + 10 + f_{1}+ 15 + f_{2} = 70$ $\Rightarrow f_{1}+f_{2} = 37\quad\ldots\left(i\right)$ and $\bar{x} = \frac{\Sigma fx}{\Sigma f}$ $\Rightarrow 5f_{1}+9f_{2} = 277\quad\ldots\left(ii\right)$ Solving $\left(i\right)$ and $\left(ii\right)$, we get $f_{1} = 14$ and $f_{2} = 23$