Our class has 21 students of which 9 are civil engineering majors. suppose i need to randomly select one student per day from this class to have lunch with me. (a) assume that i require five different students from monday to friday. let x be the number of students of the sample of 5 that are civil engineering majors. what is the appropriate random variable to model x? what is e(x)? (b) assume that i do not require five different students. same student can go on different days. let y be the number of times from monday to friday that i have lunch with civil engineering majors. what is the appropriate random variable to model y ? what is e(y )?