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
(1) an odd number ?
(2) a multiple of 5 ?

Answer 1

Digits are 23,25,27,29,32,33,35,37,39,52,53,55,57,59,72,73,75,77,79,92,93,95,97,99
Total digits are 25
Odd numbers are 19
Then probability is 19/25
25,35,55,75,95 are divisible by 5
Then answer is 5/25

Answer 2

Answer:

odd number = 4/5

a multiple of 5 = 1/5

Step-by-step explanation:

A two digit number is formed with digits 2, 3, 5, 7, 9 without repetition

Total number of two digits number can be formed

= 5 * 4

= 20

Odd number =  1 * 4 + 4 * 3 = 16

( if 1st digit is even then 1 * 4  + 1st digit is odd then 4 * 3)

Probability of odd number = 16/20 = 4/5

Multiple of 5

1st digit can be chosen from 4 digit other than 5

2nd digit has to be 5

4 * 1 = 4

Probability of a multiple of 5 = 4/20 = 1/5