Answer:
The probability that 200 women have a mean pregnancy between 266 days and 268 days is 0.371.
Explanation:
Let <em>X</em> = gestation time for humans.
The mean of the random variable <em>X</em> is: E (X) = <em>μ</em> = 266 days.
The standard deviation of the random variable <em>X</em> is: SD (X) = <em>σ</em> = 25 days.
**Assume that the gestation time for humans follows a Normal distribution.
The <em>z</em>-score for the sample mean is:
.
The sample of women selected is:<em> </em><em>n</em> = 200.
Compute the probability that 200 women have a mean pregnancy between 266 days and 268 days as follows:

**Use the <em>z</em>-table for the probability.
Thus, the probability that 200 women have a mean pregnancy between 266 days and 268 days is 0.371.