Probability 3 Question 31
31. A pair of fair dice is rolled together till a sum of either 5 or 7 is obtained. Then, the probability that 5 comes before 7 , is… .
(1989, 2M)
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Solution:
- 5 can be thrown in 4 ways and 7 can be thrown in 6 ways, hence number of ways of throwing neither 5 nor 7 is
Hence, required probability
