The mean and standard deviation of marks ...

NCERT Class XI Mathematics - Statistics - Solutions

Question : 33 of 34

Marks: +1, -0

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?

Solution:

For Mathematics,

\overline{x}

= 42 and σ = 12

∴ C.V. of Mathematics =

\frac{12}{42}

× 100 = 28.57

For Physics,

\overline{x}

= 32 and σ = 15

∴ C.V. of Physics =

\frac{15}{32}

× 100 = 46.88

For Chemistry,

\overline{x}

= 40.9 and σ = 20

∴ C.V. of Chemistry =

\frac{20}{40.9}

× 100 = 48.9

Thus Chemistry with highest C.V. shows the highest variability and Mathematics with lowest C.V. shows the lowest variability.

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