Question

A locker combination has three nonzero digits, and digits cannot be repeated. If the first digit is odd, what is the probability that the second digit is even?
a. 1/2B. 4/9C. 1/8D. 1/9

Answer 1

The locker key is a combination of 3 different digits from 9 numbers (1 to 9).

This contains 5 odd numbers and 4 even numbers.

If the first digit is odd, there are 4 even digits in the remaining 8 numbers.

The probability that the second digit is even is $\frac{4}{8} =\frac{1}{2}$