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Subject: Re: Probability problem  Date: 9/8/2020 12:51 PM  
Author: rev2217  Number: 5999 of 6013  
Bob, There are 3 dice in a bag: 6sided, 12sided and 20sided. We pick one die at random, roll it, and it gives us a number N. What's the probability that when we pick another die and roll it, we'll get a number smaller than N, if N = 4? This problem actually is much simpler than it appears. Regardless of which die is pulled first and whether it's replaced or not, there's a 1/3 probability of picking each die on the second selection. Each die has 3 faces that are less than 4 (values 1, 2, and 3). Thus, the probability is P = 1/3 x 3/6 + 1/3 x 3/12 + 1/3 x 3/20 = 1/6 + 1/12 + 1/20 = (10+5+3)/60 = 18/60 = 3/10. Norm. 

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