Question

A professor is interested in comparing the average amount spent on textbooks for freshmen and sophomores. A random sample of 10 freshmen yielded a sample mean amount of 1023 and a sample standard deviation of 68. A random sample of 14 sophomores yielded a sample mean amount of 1257 and a sample standard deviation of 338. Construct a 99% confidence interval for the difference between the mean amount spent on textbooks by freshmen and the mean amount spent by sophomores (ie. do freshmen minus sophomores). Since the sample standard deviations are wildly different, use a method which does not assume the populations have the same variance. Assume normality. a) What is the appropriate degrees of freedom in this case? b) What is the lower confidence limit on the interval? Give your answer to three decimal places. c) What is the upper confidence limit on the interval? Give your answer to three decimal places. d) Using this interval, is it reasonable to conclude that the average sophomore spends more than the average freshman? A. Yes because the upper endpoint on the interval is above 0. B. Yes because the upper endpoint on the interval is below 0. C. Yes because the interval contains 0. D. No because the interval contains 0.

Answer 1

Answer:

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