The quality-control manager at a factory that manufactures memory cards for

digital cameras needs to determine whether the mean data-transfer rate of a large shipment of cards is equal to 10 MB/s. The population standard deviation is 0.8 MB/s. A random sample of 64 cards indicates a sample mean data transfer rate of 9.8 MB/s.

(a) Consider the question: Is there evidence that the mean data-transfer rate is different from 10 MB/s? Would you recommend a hypothesis test with a one or two-sided alternative hypothesis? Justify your answer and write down your alternative hypothesis.

(b) Use your hypothesis test from part (a) to answer the question: Is there evidence that the mean data-transfer rate is different from 10 MB/s?

(c) What (if any) assumptions are needed in order for your conclusions in part (b) to be reliable?

(d) Construct a 95% confidence interval for the mean data-transfer rate of the large shipment of cards.