The problem first gives conditions: given that an urn contains n orange balls and n yellow balls, and two are selected at random.(adsbygoogle = window.adsbygoogle || []).push({});

The question was to determine the probability of getting two balls of different colors.

I did (1)*(n)/(2n-1)

Where 1 represented the probability of getting either color and the other term represented getting a ball of different color.

Anyway the answer was right but the book explained it in a way that i didn't understand. They said that there are n^2 chances of getting orange and then yellow and n^2 chances of getting yellow then orange. They divided this by the total possilbe which was 2n(2n-1)

[n^2+n^2]/2n(2n-1)

Can someone explain to me why n^2 equals what it equals. Thank you.

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# Homework Help: Urn problem

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