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CMA Final · Strategic Cost Management · Introduction to Tools for Data Analytics

A Pune retailer's monthly sales (in ₹ lakh) over five months were 20, 22, 24, 26 and 28. An analyst computes the mean and the sample standard deviation (divisor n-1) of these figures. What is the sample standard deviation?

The sample standard deviation is about 3.16. The mean is 24, the squared deviations total 40, and dividing by n-1 equals 4 gives a variance of 10, whose square root is 3.16. Dividing by 5 would give the population figure of 2.83.

  1. A2.00
  2. B3.16Correct
  3. C2.83
  4. D4.00

Explanation

Mean = 24. Squared deviations: 16, 4, 0, 4, 16 = 40. Sample variance = 40/4 = 10, so SD = √10 = 3.16. Using n as divisor gives 40/5 = 8, √8 = 2.83, which is the population SD and is wrong here.

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