CoCo S.A. is concerned about the time taken to react to customer complaints and has implemented a new set of procedures for its support centre staff . The customer service director has decided that there is no evidence for the population distribution to be normally distributed and has directed that a suitable test is applied to the sample to assess whether the new target mean time for responding to customer complaints is 28 days (Table 7.23).

(a) Describe the test to be applied with stated assumptions.

(b) Conduct the required test to assess whether evidence exists for the mean time to respond to complaints to be greater than 28 days.

(c) What would happen to your results if the population mean time to react to customer complaints changes to 30 days?

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20 40 32 15 31 28 32 Table 7.23 33 33 50 33 35 22 34 33 20 36 27 19 26 39 29 39 31 29 39 42 39 24 32 38 43 22 30 32 30 37 29 33 21 17 38