Question

The numbers $4$ and $9$ have frequencies $x$ and $(x-1)$ respectively If their arithmetic mean is $6$ then $x$ is equal to

• A. $2$
• B. $3$
• C. $4$
• D. $5$

Answer 1

Answer: (B)

$3$

Given $\frac{4x+9(x-1)}{x+(x-1)}=6$
$\Rightarrow \frac{13x-9}{2x-1}=6\Rightarrow 13x-9\Rightarrow 12x-6\Rightarrow x=3$