Question

Find the mean of the following distribution :

$\begin{array}{cccccc}x:& 4& 6& 9& 10& 15\\ f:& 5& 10& 10& 7& 8\end{array}$

• A. 7
• B. 8
• C. 9
• D. 10

Answer 1

The correct option is C

9

$\begin{array}{cccccc}x:& 4& 6& 9& 10& 15\\ f:& 5& 10& 10& 7& 8\\ f_i{x}_i:& 20& 60& 90& 70& 120\end{array}$
$Now,\sum f_i{x}_i=20+60+90+70+120=360$$\sum f_i=4+6+9+10+15=40\text{Mean}=\frac{\sum f_i{x}_i}{\sum f_i}=\frac{360}{40}=9$