2000 AIME II Problems/Problem 3
Problem
A deck of forty cards consists of four 's, four
's,..., and four
's. A matching pair (two cards with the same number) is removed from the deck. Given that these cards are not returned to the deck, let
be the probability that two randomly selected cards also form a pair, where
and
are relatively prime positive integers. Find
Solution
There are ways we can draw two cards from the reduced deck. The two cards will form a pair if both are one of the nine numbers that were not removed, which can happen in
ways, or if the two cards are the remaining two cards of the number that was removed, which can happen in
way. Thus, the answer is
, and
.
See also
2000 AIME II (Problems • Answer Key • Resources) | ||
Preceded by Problem 2 |
Followed by Problem 4 | |
1 • 2 • 3 • 4 • 5 • 6 • 7 • 8 • 9 • 10 • 11 • 12 • 13 • 14 • 15 | ||
All AIME Problems and Solutions |
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