The lengths of pregnancies are normally distributed with a mean of 268 days and a standard deviation of 15 days.

• If 1 pregnant woman is randomly selected, find the probability that the length of her pregnancy is less than 260 days.
• If 25 randomly selected women are put on a special diet just before they become pregnant, find the probability that their lengths of pregnancy have a mean that is less than 260 days (assuming the diet has no effect).
• If the 25 women above do have a mean of less than 260 days, does it appear that the diet has an effect on the length of pregnancy, and should the medical supervisors be concerned?