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We roll a fair 6-sided die 5 times. What is the probability that we get a 6 in at most 2 of the rolls?

 Jul 4, 2019
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P(rolling no 6's)  =  (5/6)^5

P(rolling one 6)  =  C(5,1) (1/6)(5/6)^4

P(rolling two 6's)  = C(5,2) (1/6)^2 (5/6)^3

 

So.....the probability is

 

(5/6)^5 + C(5,1)(1/6)(5/6)^4  + C(5,2) (1/6)^2 (5/6)^3  =  625/648 ≈  .964  ≈  96.4%

 

cool cool cool 

 Jul 4, 2019

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