3.6. Suppose census data yield the following age distribution for the county of interest in problems 3.4 and 3.5: 20–30: 20%; 30–40: 40%; 40–50: 30%; 50– 60: 10%. Calculate the post-stratified estimate of mean cholesterol, its associated standard error, and a 95% confidence interval for the population mean.

Data for Problem 3.7 xi 1 2 3 4 5 6 7 8 9 10 yi 1 4 3 2 6 10 14 ? ? ? pi 0.1 0.1 0.1 0.1 0.1 0.5 0.5 0.5 0.5 0.5 fi 1 1 1 0.9 0.9 0.8 0.7 0.6 0.5 0.1