(adapted from Exercise 25.9 ) Recall the "coils" data from Homework 9. A plant contains a large number of coil winding machines. A production analyst studied a certain characteristic of the wound coils produced by these machines by selecting four machines at random and then choosing 10 coils at random from the day's output of each selected machines. coils = read.csv("coils.csv", header=T) (a) Estimate the mean coil characteristic for all coil winding machines in the plant; use a 90% confidence interval. (b) Obtain a point estimate of 2 . (c) Interpret the intra-class correlation (ICC), 2 /( 2 2 ), in the context of this situation. Also, estimate it 90% confidence. (d) Test whether or not 2 and 2 are equal; use = 0.1. State the alternatives, decision rule, and conclusion. Hint: your answer above can be used to address this