ledolter and hogg report that two different fabrics say x and y are compared on a martindate were tester that can compare two materials in a sigle run, the weights losses from seven runs are as follows:
x= 36 26 31 38 28 37 22
y= 39 27 35 42 31 39 21
analyze these data by constructing a 90% confidence interval for the difference of the means. stat your assumption.