Question on Determing the Proportion

Can someone please help me on this problem with A,B,C,D with explanation please. Thank you in advanced! (Nod)

Data from the national Vital Statistics Report reveal that the distribution of the duration of human pregnancies is approximately normal with mean = 270 and standard deviation = 15. Use this normal model to determine the proportion of all pregnancies that come to term in:

A) less than 244 days

B) more than 275 days

C) over 300 days

D) between 260 and 280 days