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ACCA Applied Knowledge · Management Accounting · Summarising and analysing data

A company records the number of customer complaints received in each of eight weeks: 2, 4, 4, 4, 5, 5, 7 and 9. Treating these eight weeks as the whole population, what is the standard deviation?

The population standard deviation is 2.00 complaints. The mean is 5, the sum of squared deviations is 32, and dividing by 8 gives a variance of 4. The standard deviation is the square root of the variance, which is 2.

  1. A2.00Correct
  2. B4.00
  3. C2.14
  4. D5.00

Explanation

The mean is 40/8 = 5. The squared deviations are 9, 1, 1, 1, 0, 0, 4 and 16, which sum to 32. The variance is 32/8 = 4 and the standard deviation is the square root of 4 = 2. Using n-1 (32/7) gives 2.14, which is the sample formula and is not appropriate here. 4.00 is the variance, not the standard deviation.

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