Standard deviation of mathematics =12
Standard deviation of physics =15
Standard deviation of chemistry =20
The coefficient of variation (C.V) is given by StandarddeviationMean×100
Thus C.V (in mathematics )=1242×100=28.57
C.V.(in physics ) = 1532×100=46.87
C.V.(in Chemistry ) =2040.9×100=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