Question

A telemarketing company sets a guideline that the average time for each completed sales call should be no longer than 240 seconds (4 min). The manager is concerned that operators are needlessly chatting with customers, and calls are taking too long. Operators will be required to undergo additional training if the results show that calls are too long. A random sample of 12 calls showed a sample mean of 244.67 seconds with a sample standard deviation of 54 seconds (sigma unknown).

a. Write out Ho and Ha.

b. Discuss the meaning of Type I and Type II error. Use words that describe the actions that will be taken (or not) in your answer.

c. Using MegaStat, calculate the p-value and provide MegaStat output for documentation.

d. Can we reject Ho at the .05 significance level? Can we be confident that calls are taking longer than the guideline of 240 seconds at the .05 significance level? CAREFULLY EXPLAIN WHY OR WHY NOT.

Answer 1

(a) The hypothesis being tested is:

H0: µ 240

Ha: µ > 240

(b) Type I error = Rejecting that the average time for each completed sales call should be no longer than 240 seconds when it is true.

Type II error = Accepting that the average time for each completed sales call should be no longer than 240 seconds when it is false.

(c) The output is:

(d) The p-value is 0.3850.

Since the p-value (0.3850) is greater than the significance level (0.05), we cannot reject the null hypothesis.

Therefore, we cannot conclude that calls are taking longer than the guideline of 240 seconds.

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