Problem:
An envelope contains eight bills: 2 ones, 2 fives, 2 tens, and 2 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
The problems on this page are the property of the MAA's American Mathematics Competitions