Question

The marks obtained by 10 students in a subject are:
$\begin{array}{ccccccccccc}\text{Students}& \text{A}& \text{B}& \text{C}& \text{D}& \text{E}& \text{F}& \text{G}& \text{H}& \text{I}& \text{J}\\ \text{Marks}& 85& 60& 50& 75& 55& 40& 55& 70& 45& 65\end{array}$

Calculate arithmetic mean by direct method.

Answer 1

$\begin{array}{cc}\text{Students}& \text{Marks}\\ & \text{(X)}\\ \text{A}& 85\\ \text{B}& 60\\ \text{C}& 50\\ \text{D}& 75\\ \text{E}& 55\\ \text{F}& 40\\ \text{G}& 55\\ \text{H}& 70\\ \text{I}& 45\\ \text{J}& 65\\ \text{N=}10& \sum X=600\end{array}$

So Arithmetic mean = $\overline{X}=\frac{\sum X}{N}=\frac{600}{10}=60$