The duration of pregnancy in a particular human population (in a district of South India) is approximately Normally distributed with = 274.3 days and = 8.9 days. In the following questions, assume that this distribution is exact.

1. What proportion of pregnancies last between 265 and 279 days? Your answer must include a diagram and an approximation as well as a precise answer with workings.
2. What durations give the quartiles of the distribution of pregnancy durations for this population?