Question

The following table shows the marks obtained by 5 students in a class. Find the average marks of the class.

$$\begin{array}{cc}Marks& Frequency\\ 98& 1\\ 65& 1\\ 88& 2\\ 54& 1\end{array}$$

• A. 76.6
• B. 77.6
• C. 78.6
• D. 78.9

Answer 1

The correct option is C

78.6

The total marks obtained by the 5 students in the class = 98 + 65 + 176 + 54 = 393.

The mean or average marks can be calculated by dividing the total marks obtained by the students by the number of students in the class.

Mean = $\frac{Sumofobservations}{No.ofObservations}$

= $\frac{393}{5}$= 78.6

$$\begin{array}{ccc}Marks\left(x_i\right)& Frequency\left(f_i\right)& x_i{f}_i\\ 98& 1& 98\\ 65& 1& 65\\ 88& 2& 176\\ 54& 1& 54\\ Total& \sum f_i=5& \sum x_i{f}_i=393\end{array}$$

So, mean or average = $\frac{\sum 393}{\sum 5}$= 78.6