As Americans become more conscious about the importance of good nutrition, researchers theorize that the consumption of red meat may have decreased over the last 10 years. A researcher selects hospital nutrition records for 400 subjects surveyed 10 years ago and compares the average amount of beef consumed per year to amounts consumed by an equal number of subjects interviewed this year. The data are given in the table.

a. Do the data present sufficient evidence to indicate that per-capita beef consumption has decreased in the last 10 years? Test at the 1% level of significance.
b. Find a 99% lower confidence bound for the difference in the average per-capita beef consumptions for the two groups. (This calculation was done as part of Exercise 8.78.) Does your confidence bound confirm your conclusions in part a? Explain. What additional information does the confidence bound give you?

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Sample Mean Sample Standard Deviation Ten Years Ago 73 25 This Year 63 28