The mean and standard deviation of marks obtained by 50 students of a class in three subject, Mathematics, Physics and Chemistry are given below :
     
Which of the three subjects shows the highest variability in marks and which shows the lowest?

Explanation

Here, we will calculate coefficient of variation which is given by,

`C.V. = (S.D.)/(barX)**100`

Here, `S.D.` is the standard deviation and `barX` is the mean.

`:.` Coefficient of variation for Mathematics `= 12/42**100 = 200/7 = 28.57`

Coefficient of variation for Physics`= 15/32**100 = 375/8 =46.875`

Coefficient of variation for Chemistry`= 20/40.9**100 ~= 49`

As coefficient of variation for Chemistry is highest, it shows highest variability.

As coefficient of variation for Mathematics is lowest, it shows lowest variability.