MyPhone Manufacturing makes smart phones. As part of the company’s quality efforts, the company wishes to estimate the mean number of days the phone is used before repair is needed. A pilot sample of 30 phones indicates a sample standard deviation of 200 days. The company wishes its estimate to have a margin of error of no more than 20 days with a confidence level of 95%. a. Given this information, how many additional phones should be sampled? b. The pilot study was initiated because of the costs involved in sampling. Each sampled observation costs approximately $20 to obtain. Originally, it was thought that the population’s standard deviation may be as large as 300 days. Determine the amount of money saved by obtaining the pilot sample
10. MyPhone Manufacturing makes smart phones. As part of the company’s quality efforts, the company wishes to estimate the mean number of days the phone is used before repair is needed. A pilot sample of 30 phones indicates a sample standard deviation of 200 days. The company wishes its estimate to have a margin of error of no more than 20 days with a confidence level of 95%.
a. Given this information, how many additional phones should be sampled?
b. The pilot study was initiated because of the costs involved in sampling. Each sampled observation costs approximately $20 to obtain. Originally, it was thought that the population’s standard deviation may be as large as 300 days. Determine the amount of money saved by obtaining the pilot sample.
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