Problem:
An envelope contains eight bills: ones, fives, tens, and twenties. Two bills are drawn at random without replacement. What is the probability that their sum is or more?
Answer Choices:
A.
B.
C.
D.
E.
Solution:
There are
ways to choose the bills. A sum of at least is obtained by choosing both bills, one of the bills and one of the six smaller bills, or both bills. Hence the probability is
Answer: .
The problems on this page are the property of the MAA's American Mathematics Competitions