The amount of time customers at a “Quick-Change” motor oil store spend waiting for their cars to be serviced has the Normal distribution with mean \mu and standard deviation \sigma = 4 minutes. It is company policy that the customer wait time should be 20 minutes (or less). The manager of a particular store selects a random sample of 150 customer wait times and observes a mean wait time of 21 minutes. A 99% confidence interval for the population mean wait time based on this sample was calculated to be (20.16, 21.84) minutes.
If the manager had decided to have more precision in making inference on the population mean \mu , which of the following steps can the manager take to achieve the goal?

Question

The amount of time customers at a “Quick-Change” motor oil store spend waiting for their cars to be serviced has the Normal distribution with mean   \mu  and standard deviation   \sigma  = 4 minutes. It is company policy that the customer wait time should be 20 minutes (or less). The manager of a particular store selects a random sample of 150 customer wait times and observes a mean wait time of 21 minutes. A 99% confidence interval for the population mean wait time based on this sample was calculated to be (20.16, 21.84) minutes.  
 If the manager had decided to have more precision in making inference on the population mean   \mu , which of the following steps can the manager take to achieve the goal?

Answer

Use more customer wait times in the sample.

Answer

Use more decimal places in the result.

Answer

Remove outliers from the sample.

Answer

Use 95% confidence level.

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The amount of time customers at a “Quick-Change” motor oil store spend waiting ...

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