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fair 6-sided dice are simultaneously rolled. The probability that exactly two of them show a number 1 is 25/72.  Find n.

 Nov 16, 2020
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I think your probability should read: 5 / 72  NOT  25 / 72. If that is correct, then:

 

[(nC2) * 5^(n - 2)] / 6^n =5 / 72, solve for n

 

n = 3 dice.

 Nov 16, 2020

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