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.

Answer 1

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`