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Question
A die is rolled twice. Find the probability that 5 will come up exactly one time.
Solution
Total number of outcomes = 36.
Cases where 5 comes up on exactly one time are (1, 5), (2, 5), (3, 5), (4, 5), (5, 1), (5, 2), (5, 3), (5, 4), (5, 6) and (6, 5).
Number of such cases = 10.
∴ P(5 will come up exactly one time) = `("Number of favourable outcomes")/"Number of all possible outcomes"`
`= 10/36 = 5/18`
Thus, the probability that 5 will come up exactly one time is `5/18`.
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