Consider the data from the experiment of Example 9.2-3, which compares the strengths of two types of steel. Thus, the n1 = 32 cold-rolled steel observations yield X1 = 29.8, S1 = 4.0, and the n2 = 35 two-sided galvanized steel observations yield X2 = 34.7, S2 = 6.74. Are the mean strengths of the two types of steel different?

(a) Test at level α = 0.01 and compute the p-value.

(b) Use ss=read.table(”SteelStrengthData.txt”, header=T) to read the data into the R data frame ss, then use R commands to conduct the test of part

(a) and to construct a 99% CI.