Question

The mean of the following distribution is: 16.5

$$\begin{array}{ccccc}{x}_i& 15& 12& 18& 19\\ f_i& 2& 5& 7& 6\end{array}$$

• A. 15.2
• B. 15.35

Answer 1

The correct option is A

15.2

Average or mean value of a given number of observations is the sum of all the observations divided by the total number of observations. So,
$\text{mean}=$ $\frac{sumofallobservations}{numberofobservations}=$ $\frac{\sum x_i{f}_i}{\sum f_i}$
So,
$\sum x_i$$f_i$
= 30 + 60 + 126 + 114 = 330
and
$\sum f_i=20$

So,
$\text{mean}=\frac{\sum x_i{f}_i}{\sum f_i}=\frac{330}{20}=16.5$