Given that the set of numbers is used to form a two-digit number,
determine the probability of having a number whose units or tens digit is an odd number.
The probability of event occurring is equal to the number of favorable outcomes divided by the total number of possible outcomes in the sample space, .
In this case, event is forming a two-digit number whose units or ten digit, or both, is an odd number.
Also, the sample space is ,
so the favorable outcomes for event are 11, 12, 14, 18, 21, 41, and 81. Find the probability of event as follows:
Thus, the probability of forming a two-digit number whose units or ten digit, or both, is an odd number is .