- #1

member 587159

## Homework Statement

I have 3 yellow and 7 blue marbles. I put those randomly in a line. What is the probability that no yellow marbles are next to each other?

## Homework Equations

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## The Attempt at a Solution

Total amount of opportunities to put those marbles next to each other: 120

Total amount of opportunities to put 3 marbles next to each other: 8

Total amount of opportunities to put 2 marbles next to each other:

(9 nCr 1)*(8 nCr 1) = 72

72 - (8 nCr 1) = 64

1 - (64+8)/120 = 2/5

Can someone verify whether I'm correct? Or at least tell me where I am wrong?