25
(2)
5 3
3
35
Operation Display
<Example 2>
(1)
When three cards are selected from five cards numbered
1 to 5 and placed in a row, how many possible orderings of
the cards are there?
(2)
When three cards are selected from five cards numbered
1 to 5, how many ways of selecting the cards are possible?
5
P
3
= 5 x 4 x 3
Let the number of ways of selecting the cards be C.
There are 3! possible orderings of the cards, and thus
when ordered in a row
Therefore C is
(1)
5
3
Permutations, Combinations
*This is written as
5
C
3
.
C x 3! =
5
P
3
C =
5
P
3
÷ 3!
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