### Question Description

Time. A.1680 B.56 C.6720 D.109

## Explanation & Answer

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Since order does matter (this is because the word "cab" is different than "abc"), we can use the permutation formula:

Start with the given formula

Plug in (this is number of letters given) and (this is the number of letters we can use together at a time)

Subtract to get 5

Expand 8!

Expand 5!

Cancel

Simplify

Now multiply 8*7*6 to get 336

So 8 choose 3 (where order does matter) yields 336 unique combinations

Expand 5!

Cancel

Simplify

Now multiply 8*7*6 to get 336

So 8 choose 3 (where order does matter) yields 336 unique combinations

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