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Visitor 1550041421 posted an answer
10 months, 1 day ago

Let's assume you have one red die and one blue die. Whatever number the red die shows, if the blue die lands on the opposite side, the two numbers will add up to 7. Thus there is a 1/6 chance of rolling a 7.

In order to roll an 11, you need the red die to be either a 5 or a 6. There is a 1/3 chance of this. Once that happens, you have a 1/6 chance of the blue die being the other number that adds to 11. (The red die could be either a 5 or a 6 but the blue die can only be the one the red die is not.) 1/3 * 1/6 = 1/18.

If we add the chances of a 7 (1/6) and an 11 (1/18) we get 3/18 + 1/18 = 4/18 or 2/9.
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