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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 subjects shows the highest variability in marks and which shows the lowest?
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Solution
We know: \[CV = \frac{\sigma}{\bar{X}} \times 100\]
\[\bar{{X_m}} = 42, \sigma_m = 12\]
\[ \bar{{X_p}} = 32, \sigma_p = 15\]
\[ \bar{{X_c}} = 40 . 9, \sigma_c = 20\]
CV of mathematics marks
Since CV of chemistry is the greatest, the variability of marks in chemistry is the highest and that of mathematics is the lowest.
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