THE TRASH BAG CASE DS TrashBag
The mean and the standard deviation of the sample of 40 trash bag breaking strengths in Table 1.9 are x = 50.575 and s = 1.6438.
a. Use the Excel output in Figure 8.15 to calculate a t-based 95 percent confidence interval for m, the mean of the breaking strengths of all possible new trash bags. Are we 95 percent confident that m is at least 50 pounds?
b. Assuming that the population of all individual trash bag breaking strengths is normally distributed, estimate tolerance intervals of the form [m + za/2 s] that contain (1) 95 percent of all individual trash bag breaking strengths and (2) 99.8 percent of all individual trash bag breaking strengths.
Text Book: Business Statics in Practice By BOWERMAN.