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Question
A two digit number is formed with digits 2, 3, 5, 7, 9 without repetition. What is the probability of the following events?
Event A : The number formed is an odd number.
Event B : The number formed is a multiple of 5.
Solution
S = {23, 25, 27, 29, 32, 35, 37, 39, 52, 53, 57, 59, 72, 73, 75, 79, 92, 93, 95, 97}
n(S) = 20
A = {23, 25, 27, 29, 35, 37, 39, 53, 57, 59, 73, 75, 79, 93, 95, 97}
n(A) = 16
P(A) = `(n(A))/(n(s))`
= `16/20`
= `4/5`
B = {25, 35, 75, 95}
n(B) = 4
P(B) = `(n(B))/(n(s))`
= `4/20`
= `1/5`
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