2. The length of human pregnancies from conception to birth varies according to a distribution that is approximately normal with mean 264 days and standard deviation 16 days. a. What's the probability a pregnancy lasts less that 250 days?

Aresearch study is done to find the average age of all u. s. factory workers. the researchers asked every factory worker in ohio what their birth year is. this research is an example of a census survey convenience sample simple random sample