Question

You forgot the last two digits of your friends phone number. You know that the next to last digit is 4 or 5, and the last digit is an odd number. If you guess the phone number what is the probability that you will be correct?

Answer 1

If you did the math right there is a 90% sure that you have got it right and a 10% that you have not

Answer 2

1/10 or 10%

Explanation:

There are a total of five odd digits we can use (1,3,5,7,9). And we know the second to last digit is a four or a five. That means there is a total of 10 combinations (5 for each secondary digit). A guess would give you one of those ten combinations. Giving you a probability of 1/10 or 10%.