Question

In how many ways can you arrange 6 CD’s from a collection of 50 CD’s?

Answer 1

The word "arrangement" indicates that the order of selection matters in this problem. There are 50 ways to choose the first CD, 49 for the second, 48 for the third, 47 for the fourth, 46 for the fifth, and 45 for the sixth CD.
By the Fundamental Principle of Counting, there are 50*49*48*47*46*45 ways to select and arrange the six CDs.
50*49*48*47*46*45 = 11 ,441 ,304 ,000 ways to do this.
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If the question had read "How many ways can you choose a group of 6 CDs from a set of 50," the answer would be a combination of 50 taken 6 at the time which is 15, 890, 700.