Question 1.102

1.102 Length of pregnancies.

The length of human pregnancies from conception to birth varies according to a distribution that is approximately Normal with mean 266 days and standard deviation 16 days.

  1. What percent of pregnancies last fewer than 240 days (that is, about 8 months)?
  2. What percent of pregnancies last between 240 and 270 days (roughly between 8 and 9 months)?
  3. How long do the longest 20% of pregnancies last?