Answer
1) The proportion of the lengths of human pregnancies that are greater than 280 days is 0.1908.
2) The probability that a randomly select human pregnancy has its length greater than 280 days is 0.1908.
Work Step by Step
1) $\frac{lengths~of~human~pregnancies~greater~than~280~days}{total~number~of~observed~pergnacies}=0.1908$
2) $P(X\gt280)=0.1908$
