Question

Assume that 2 digits are selected
at random from the set {1,3,5,7,9} and are arranged in random order. What is the probability that the resulting 2-digit number is less than 90?

Answer 1

from 2 digits are selected, each number can repeat or no?

Answer 2

i'm going to assume they can repeat.

Answer 3

OK..

Answer 4

for solution :
Probability of an event happening = Number of ways it can happen/Total number of outcomes
= 4(5)/5(5) = 20/25 = 4/5