Question 1.97

1.97 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. Use the 68-95-99.7 rule to answer the following questions.

  1. Between what values do the lengths of the middle 95% of all pregnancies fall?
  2. How short are the shortest 2.5% of all pregnancies?

1.97

(a) 95% of pregnancies last between 234 and 298 days. (b) The shortest pregnancies are 234 days or less.