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Two groups A and B have the following frequency distributions over the class marks (class intervals 10-20 to 70-80). Group A frequencies: 9, 17, 32, 33, 40, 10, 9. Group B frequencies: 10, 20, 30, 25, 43, 15, 7. Using the coefficient of variation, which group is more variable?

1. Group A
2. Group B
3. Both are equally variable
4. Cannot be determined

Correct answer: Group B

Solution

Computing means and standard deviations from the frequency tables gives nearly equal means but a higher coefficient of variation for Group B, so Group B is more variable.

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