A simple random sample of sizenis defined to be A.a sample of sizenchosen in such a way that every set ofnunits in the population has an equal chance to be the sample actually selected. B.a sample of sizenchosen in such a way that every unit in the population has a known nonzero chance of being selected. C.a sample of sizenchosen in such a way that every unit in the population has the same chance of being selected. D.All of the above. They are essentially identical definitions.

(b) A small college has 500 male and 600 female undergraduates. A simple random sample of 50 of the male undergraduates is selected, and, separately, a simple random sample of 60 of the female undergraduates is selected. The two samples are combined to give an overall sample of 110 students. The overall sample is A.a stratified random sample. B.convenience sampling. C.a simple random sample. D.a multistage sample.

(c) In order to take a sample of 1200 people from a population, I first divide the population into men and women, and then take a simple random sample of 500 men and a separate simple random sample of 700 women. This is an example of a A.stratified random sample. B.convenience sampling. C.a simple random sample. D.a multistage sample.