This is the probability that they are both "O", plus that they are both "A",

plus that they are both "B", plus that they are both "AB".

so:

probability that astudent is not "AB" is 1 minus the probability that they are "AB", then the prob that none of them are "AB" is:1b) what is the probability that none of the first five people in line up have the type AB blood?

I m not sure how to do this question?

RonL