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 subject shows the highest variability in marks and which shows the lowest?

Answer 1

For Mathematics:

\(\bar x\) = 42, σ = 12

∴ CV of Mathematics = \(\frac{12}{42} \times 100\) = 28.57%

For physics:

\(\bar x\) = 32, σ = 15

∴ CV of Physics = \(\frac{15}{32} \times 100\) = 46.88%

For Chemistry:

\(\bar x\) = 40.9, σ = 20

∴ CV of Chemistry = \(\frac{20}{40.9} \times 100\) = 48.9%

Thus Chemistry with highest CV shows highest variability and Mathematics with lowest CV shows lowest variability.