Probability of Rolling 2 At Least TwiceDate: Wed, 3 Jul 1996 18:22:11 -0400 (EDT) From: Anonymous Subject: probability of rolling 2 twice A fair die is rolled three times. Find the probability of rolling a "two" at least twice. Thanking you ahead of time, Dr. Math. Date: Thu, 4 Jul 1996 12:43:49 -0400 (EDT) From: Dr. Anthony Subject: Re: probability of rolling 2 twice At least twice means two OR three times. We use the binomial probability distribution, with p (probability of success)= 1/6, q (probability of failure) = 5/6 and n (number of trials) = 3 P(2) = 3_C_2*(1/6)^2*(5/6) = 3*(1/36)*(5/6) = 15/216 P(3) = 3_C_3*(1/6)^3*(5/6)^0 = 1*1/216*1 = 1/216 So P(2) + P(3) = 16/216 = 2/27 -Doctor Anthony, The Math Forum |
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