The mean sand 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 ?

Standard deviation of mathematics $=12$
Standard deviation of physics $=15$
Standard deviation of chemistry $=20$
The coefficient of variation (C.V) is given by  $\frac{Standarddeviation}{Mean}\times 100$
Thus C.V (in mathematics )=$\frac{12}{42}\times 100=28.57$
C.V.(in physics ) = $\frac{15}{32}\times 100=46.87$
C.V.(in Chemistry ) =$\frac{20}{40.9}\times 100=48.89$
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