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Four packages are delivered to four houses, one to each house. If these packages are randomly delivered, what is the probability that exactly two of them are delivered to the correct houses? Express your answer as a common fraction. i tried C(4,2) times 1/4 times 1/4 times 3/4 times 3/4, but that didnt work. 

 Aug 1, 2021
edited by HELPplzplzplz  Aug 1, 2021
 #1
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I THINK there are 24 possible delivery combinations

...for exactly two to be correct:

 

1 1 x x

x 1 1 x

x x 1 1

1 x x 1

1 x 1 x

x 1 x 1            6 ways to deliver two correctly      6 / 24 = 1/4

 Aug 1, 2021
 #2
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Thanks! 

 Aug 1, 2021

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