申論題

5. (10%) A simple random sample of 500 students from a university was selected to estimate the mean living expense during last academic year. Another simple random sample of 550 students was selected, independently of the first, to estimate the mean living expense during this academic year. The sample results (expressed in thousand dollars) were as follows:

Construct a 95% confidence interval for μ₂ - μ₁. Can one conclude that the mean living expense  per student has changed between the two years at α = 0.05?