Suppose we want to choose 4 colors, without replacement, from 17 distinct colors. \[ \text { (a) How many ways can this be done, if the order of the choices is taken into consideration? } \] (b) How many ways can this be done, if the order of the choices is not taken into consideration? \( \square \)
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To approach the problem, let's dive into the colorful world of combinations and permutations! When selecting 4 colors from 17 distinct colors with order considered, we use permutations since the arrangement matters. The formula for this is given by \(P(n, r) = \frac{n!}{(n-r)!}\), where \(n\) is the total number of colors, and \(r\) is the number of colors we want to choose. Plugging in the numbers, we have: \[P(17, 4) = \frac{17!}{(17-4)!} = \frac{17!}{13!} = 17 \times 16 \times 15 \times 14 = 57120.\] Now for the second part, when order does not matter, we use combinations. The formula is \(C(n, r) = \frac{n!}{r!(n-r)!}\). So for our case: \[C(17, 4) = \frac{17!}{4!(17-4)!} = \frac{17!}{4! \cdot 13!} = \frac{17 \times 16 \times 15 \times 14}{4 \times 3 \times 2 \times 1} = 2380.\] So, to summarize, there are 57,120 ways when order counts and 2,380 ways when it doesn't!