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. He obtained: 7.65- 7.60 7.65 7.70 7.55 7.55 7.40 7.40 7.50 7.50 The quality control specialist's hypotheses are: 4. Researchers are interested in the mean age of a certain population. A random sample of 36 individuals drawn from the population of interest has a mean of 25. Assuming that the population is approximately normally distributed with variance 36, can we conclude that the mean is different from 28 years? (Use a=0.01)