**Using R.

1. Foresters want to estimate the average age of trees in a stand. Determining age is cumbersome because one needs to count the tree rings on a core taken from the tree. In general, though, the older the tree, the larger the diameter, and diameter is easy to measure. The foresters measure the diameter of all 1132 trees and find that the population mean equals 10.3 inches. They then randomly select 20 trees for age (in years) measurement.

a) Using a regression estimator, estimate the population mean age of trees in the stand and give a bound on the error of estimation.

b) Repeat part a) but use a ratio estimator instead of a regression estimator

c) Repeat part a) but use a difference estimator.

d) Which estimator should be used? Justify your answer.