Question

The mean and standard deviation of marks obtained by 50 students of a class in three subjects, Mathematics, Physics and Chemistry are given below:

Subject	Mathematics	Physics	Chemistry
Mean	42	32	40.9
Standard deviation	12	15	20

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

Answer 1

Standard deviation of Mathematics = 12

Standard deviation of Physics =15

Standard deviation of Chemistry = 20

The coefficient of variation (C.V.) is given by $\frac{Standard\,deviation}{Mean}×100$

$C.V(in\,Mathematics)=\frac{12}{42}×100=28.57$

$C.V(in\,Physics)=\frac{15}{32}×100=46.87$

$C.V(in\,Chemistry)=\frac{20}{40.9}×100=48.89$

The subject with greater C.V. is more variable than others.

Therefore, the highest variability in marks is in Chemistry and the lowest variability in marks is in Mathematics.