Question

The frequency distribution of discrete data is given below, the frequency $x$ against value $0$ is missing
If the mean is $2.5$, then the missing frequency $x$ will be
$\begin{array}{ccccccc}\text{Variable}& 0& 1& 2& 3& 4& 5\\ \text{Frequency}& x& 20& 40& 40& 20& 4\end{array}$

• A. $0$
• B. $1$
• C. $3$
• D. $4$

Answer 1

The correct option is D $4$

$\frac{\sum f_i{x}_i}{\sum f_i}=2.5\Rightarrow \frac{0\times x+1\times 20+2\times 40+3\times 40+4\times 20+5\times 4}{124+x}=2.5\Rightarrow \frac{320}{2.5}=124+x\therefore x=4$