7. A cigarette manufacturer sent each of two laboratories presumably identical samples of tobacco. Each made five determinations of the nicotine content in milligrams as follows: sample 1 : 24, 27, 26, 21 and 24 sample 2 : 27, 28, 23, 31 and 26 (a) (5 points) Were the two laboratories measuring the same thing? (Assume normality and common variance.) Be sure to state the null and alternative hypothesis and to interpret the result. Use a = 0.05. (b) (5 points) Compute a 95% confidence interval for the difference in two means