SOLUTION: 2.1 What determines use of t-distribution and z-distribution in confidence interval calculation? 2.2 A travel agency call Centre wants to know the average of calls received by

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Question 1145276: 2.1 What determines use of t-distribution and z-distribution in confidence interval calculation?
2.2 A travel agency call Centre wants to know the average of calls received by its call Centre. A random sample of 21 days is selected and the sample mean number of calls received was found to be 166.2 with a sample standard deviation of 22.8 calls. Assume that calls received daily are normally distributed.
2.2.1 Calculate a 95% confidence interval for the mean number of daily calls received by the call Centre.
2.2.2 Find the 99% confidence interval for the mean number of daily calls received by the call Centre.
2.2.3 Compare the differences in in your answers in i & ii and briefly explain the cause.
2.3 For a sample of 256 owners of medium-sized cars, it was found their average monthly car monthly car insurance premium for comprehensive cover was R356. Assume that the population standard deviation is R44 per month and that insurance premiums are normally distributed.
2.3.1 Find the 95% confidence interval for the average monthly comprehensive car insurance premium paid by all owners of medium - sized cars.

Answer by ikleyn(52781) About Me  (Show Source):
You can put this solution on YOUR website!
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