In terms of the combinations equation below, the number of possible options for each category is equal to the number of possible combinations for each category since we are only making 1 selection; for example C (8,1) = 8, C (5,1) = 5 and C
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Permutations and combinations
B = { b 1, b 2, b 3,, b n }. To define a one-to-one mapping from A to B, we have n options for f ( a 1), i.e., f ( a 1) ∈ B = { b 1, b 2, b 3,, b n }. Given f ( a 1), we have n − 1 options for f ( a 2) , and