**USING R**

A report from the Census Bureau in October 1994 provided data on new one-family houses for a sample of 28 metropolitan statistical areas (MSAs) and consolidated metropolitan statistical areas (CMSAs) from around the country. (CMSAs tend to be larger than MSAs and can be subdivided into other metropolitan areas for purposes of census data summaries). Data on total housing units sold, median sales price, and median floor area per house are available via a link on BB Learn. The median sales price can be thought of as a typical price for that area. Similarly, the median sales price thought of as a typical floor area for houses in that area. There were 250 MSAs and 18 CMSAs in the US for the year in which these data were reported.

a) Treating these data as a stratified random sample, with the MSAs and CMSAs being the two strata, estimate the mean typical sales price per house for all metropolitan areas of the US. Calculate a bound for the error and interpret your confidence interval in context of the problem.

b) Estimate the total number of houses sold in all metropolitan areas of the United States in 1993 and calculate a bound on the error. Interpret your confidence interval in context of the problem.