Chapter 8, Problem 10RP

Baby Weight. The paper “Are Babies Normal?” by T. Clemons and M. Pagano (The American Statistician, Vol. 53, No. 4, pp. 298–302) focused on birth weights of babies. According to the article, for babies born within the “normal” gestational range of 37–43 weeks, birth weights are normally distributed with a mean of 3432 grams (7 pounds 9 ounces) and a standard deviation of 482 grams (1 pound 1 ounce). For samples of 15 such birth weights, identify the distribution of each variable.

a. $\frac{\bar{x}-3432}{482/\sqrt{15}}$

b. $\frac{\bar{x}-3432}{s/\sqrt{15}}$