posted by sarah .
Assume that there is an urn containing seven $50 bills, six $20 bills, five $10 bills, four $5 bills, and one $1 bill and that the bills all have different serial numbers so that they can be distinguished from each other. A person reaches into the urn and withdraws one bill and then another;
a) in how many ways can two $20 bills be withdrawn
b) how many different outcomes are possible
c) what is the probability of selecting two $20 bills?