1. A combination selects elements from a single set.

2. Repetitions are not allowed.

3. The order in which the elements are arranged is NOT significant.

Example 1:

A group of 5 is selected from 5 boys and 6 girls. How many groups are possible
if there must be at least 3 boys in the group?

The group has at least 3 boys when it has three, four, OR five boys. We must
compute the number of groups possible with three, four, and five, and add
(OR):

3 boys and 2 girls: C (5,3) x C (6,2) = 10 x 15 = 150

4 boys and 1 girls: C (5,4) x C (6,1) = 5 x 6 = 30

5 boys and 0 girls: C (5,5) x C (6,0) = 1 x 1 = 1

The total is 150 + 30 + 1 = 181

Example 2:

How many 5-card hand can be formed from a deck of 52 cards?

The order of the cards is NOT important. Therefore, we must find the number
of combinations denoted by C (52,5).

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