Chapter 18, Problem 39E

(a)

To determine

To explain why it may be somewhat skewed to the left.

Explanation of Solution

It is given in the question that we have assume that the duration of human pregnancies can be described by a normal model with mean $266$ days and standard deviation $16$ days. Now, we have assume that the duration of human pregnancies may not actually follow the Normal model. So, the distribution of pregnancies may be skewed left since there are more premature births than there are very long pregnancies.

(b)

To determine

To explain does that change your answer in the previous exercise if the correct model is in fact skewed and explain why or why not.

Answer to Problem 39E

Yes, it the answer in part (a) and (b) will change and part (c) will remain the same.

Explanation of Solution

It is given in the question that we have assume that the duration of human pregnancies can be described by a normal model with mean $266$ days and standard deviation $16$ days. Now, we have assume that the duration of human pregnancies may not actually follow the Normal model. Thus, we can say that part (a) and (b) of previous exercise would no longer be appropriate since the normal model is not appropriate for skewed distributions. However, part (c) of the previous exercise is still valid because the Central Limit Theorem states that the sample distribution will be normal with a large enough sample.