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How many different pairs of 2 cookies can he choose from the 6?

How many different pairs of 2 cookies can he choose from the 6?-example-1

1 Answer

4 votes

Since there are 6 different cookies, the cookies can be A, B, C, D, E, F

If we select a pair of 2 different cookies, they can be AB and BC

We can see that AB and BA would be the same pair. Thus, order does not matter. When selecting items, if order doesn't matter, we apply combination. The number of possible combinations of r items from a total of n items is expressed as

nCr = n!/(r!(n - r)!

In this case,

n = 6

r = 2

6C2 = 6!/(2!(6 - 2)! = 720/(2 x 24) = 720/48

6C2 = 15

Option B is correct

User Reza Hajianpour
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