An experiment was conducted to investigate how the

Chapter 9, Problem 9.3.16

(choose chapter or problem)

An experiment was conducted to investigate how the corrosion properties of chilled cast iron depend upon the chromium content of the alloy. A collection of n = 12 samples of chilled cast iron with 0.1% chromium content provided corrosion rates with a sample mean of x = 2.462 and a sample standard deviation of sx = 0.315, while a collection of m = 13 samples of chilled cast iron with 0.2% chromium content provided corrosion rates with a sample mean of y = 2.296 and a sample standard deviation of sy = 0.297. (a) Conduct a hypothesis test to investigate whether there is any evidence that the chromium content has an effect on the corrosion rate of chilled cast iron. (b) Construct a 99% two-sided condence interval for the difference between the average corrosion rates of chilled cast iron at the two chromium contents.