Probability of A or B (3 of 3)

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The probability of getting a number from 1 to 5 on the first roll is 5/6. Likewise, the probability of getting a number from 1 to 5 on the second roll is 5/6 . Therefore, the probability of getting a number from 1 to 5 on both rolls is: 5/6 x 5/6 = 25/36. This means that the probability of not getting a 1 to 5 on both rolls (getting a 6 on at least one roll) is:

1-25/36 = 11/36.

Despite the convoluted nature of this method, it has the advantage of being easy to generalize to three or more events. For example, the probability of rolling a die three times and getting a six on at least one of the three rolls is:

1 - 5/6 x 5/6 x 5/6 = 0.421

In general, the probability that at least one of k independent events will occur is:

1 - (1 - α)k

where each of the events has probability α of occurring.

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