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Question
A two digit number is formed with digits 2, 3, 5, 7, 9 without repetition. What is the probability that the number formed is a multiple of 5 ?
Solution
Sample Space (S) = {23, 25, 27, 29, 32, 35, 37, 39, 52, 53, 57, 59, 72, 73, 75, 79, 92, 93, 95, 97}
∴ n(S) = 20
Event B: the number is a multiple of 5
B = {25, 35, 75, 95}
∴ n(B) = 4
`therefore P (B) = (n(B))/(n(S))`
` = 4/20`
`=1/5`
Hence, the probability that the number is a multiple of 5 is `=1/5`.
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