Find the number of ways to listen to four CDs from a selection of 8 CDs.? A. 1680 B. 336 C. 70 D. 50

1 Answer
George C.
May 11, 2018

#""^8P_4 = 1680#, i.e. choice A.

Explanation:

Note that the order of the CDs does matter, so we are wanting #""^8P_4# rather than #""^8C_4# ...

#""^8P_4 = (8!)/((8-4)!) = 8*7*6*5 = 1680#

In other words, there are #8# choices for the first CD, #7# for the second, #6# for the third and #5# for the fourth.

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