141 Z Test and T Test Determine which hypothesis test to use, and then carry out the 9 steps of hypothesis testing procedure. 3. A manufacturer claims that the thickness of the spearmint gum it produces is 7.5 one- hundredths of an inch. A quality control specialist regularly checks this claim. On one production run, he took a random sample of N = 10 pieces of gum and measured their thickness. Test the manufacture's claim by testing to see if there is a difference between the population mean and the sample mean. Gum's Gum Thickness ID # X #1 7.65 #2 7.60 #3 7.65 #4 7.70 #5 7.55 #6 7.55 #7 7.40 #8 7.40 #9 7.50 #10 7.50 4. Last year's tests of gums chewed showed that the consistency would last on average for 24 minutes with a standard deviation of 5.5 minutes. In a test of 36 randomly selected new gums, the gums lasted on average for 21.5 minutes. Use a of 0.01 significance level to test the claim that the new average is different from the mean of 24 minutes