Question

The mean standard deviation of marks obtained by 50 students. of a class in three subjects, Mathematics, Physics and Chemistry are given below : $\begin{array}{cccc}\text{Subject}& \text{Mathematics}& \text{Physics}& \text{Chemistry}\\ \text{Mean}& 42& 32& 40.9\\ \text{Standard deviation}& 12& 15& 20\end{array}$

Which of the three subjects shows the highest variability in marks and which shows the lowest ?

Answer 1

For mathematics

$\overline{x}=42and\sigma =12$

$\therefore$ C.V. of Mathematics = $\frac{12}{42}\times 100=28.57\%$

For Physics

$\overline{x}=32and\sigma =15$

$\therefore$ C.V. of Physics = $\frac{15}{20}\times 100=46.88\%$

For Chemistry

$\overline{x}=40.9and\sigma =20$

$\therefore$ C.V. of Chemistry = $\frac{20}{40.9}\times 100=48.9\%$

Thus chemistry with highest C.V. Shows highest variability and mathematics with lowest C.V. shows lowest variability