Suppose It Is Desired to Estimate the Average Time a Customer

Multiple Choice

Suppose it is desired to estimate the average time a customer spends in a particular store to withir 5 minutes (e.g., $\pm 5$ minutes) at $99 \%$ reliability. It is estimated that the standard deviation of the times is 15 minutes. How large a sample should be taken to get the desired interval?

A) $n = 35$
B) $n = 25$
C) $\mathrm { n } = 60$
D) $\mathrm { n } = 299$