A restaurant claims that the standard deviation in the length of serving

A local telemarketer surveyed 100 homes and, based on the survey, obtained a sample mean. The population mean is known to be 50 and the population standard deviation is also known to be 5. It is determined that the probability of exceeding the sample mean obtained in the survey is 0.075. Assume that the z-value arrived at is positive. What is the sample mean?

a. 1.44 b. 49.28 c. 50.72 d. 57.20

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