PLS HELPPPP A sample of 70 students need to be selected from 500 freshmen from college of Engineering to start the study. These freshmen are from three different department. Department of Railway Engineering have 150 freshmen. Department of Civil Engineering have 250 and Department of Computer Engineering have 100.

a. What sampling technique we will use to choose the 70 students needed on the study?

b. Solve the three strata.

c. Suppose the researchers decided to down the sample to 50, how many freshmen will be needed now to the Department of Computer Engineering?