The mean weight gain during pregnancy is 30 pounds, with a standard deviation of 12.9 pounds. Weight gain during pregnancy is skewed right. An obstetrician obtains a random sample of 35 low-income patients and determines their mean weight gain during pregnancy was 36.2 pounds. Does this result suggest anything unusual?

Approach We want to know whether the sample mean obtained is unusual. Therefore, determine the likelihood of obtaining a sample mean of 36.2 pounds or higher (if a 36.2-pound weight gain is unusual, certainly any weight gain above 36.2 pounds is also unusual). Assume that the patients come from the population whose mean weight gain is 30 pounds. Verify the independence assumption. Use the normal model to obtain the probability since the sample size is large enough to use the Central Limit Theorem. Determine the area under the normal curve to the right of 36.2 pounds with

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12.9 == =30 and x n 35