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I am having a bit of a problem with the following question: There are 16 balls, 5 red, 8 blue, and 3 green. The result is the ordered list of the first 4 balls only (although all balls have been drawn). I am able to determine the number of possible results, and the number of results if all the first four marbles are the same color. The issue is how to determine the number of combinations of when both the first and fourth balls are one color (say red) and the number of combinations where the first two balls drawn are different colors.

If possible, I would like to see the "how" you determine this, since I have been running through these problems multiple times and am becoming frustrated.

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    Let me get this straight. You want to know how many ways I can select 4 balls, in order, from those 16 balls, such that the first and fourth are the same color, and such that the first two balls are different colors. For example, two such elements would be RBGR and RGGR. So the different numbers mean nothing. Is that correct?2012-07-25
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    Are marbles the same as balls? More important, are the 5 red objects distinguishable from each other? similarly, the 8 blue? the 3 green?2012-07-25

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