A passcode contains 3 digits from 0-9. What is the probability of randomly selecting a passcode where the first digit is NOT zero and the last digit is even?
1 Answer
Mar 4, 2018
Explanation:
If we were able to select from all the digits in all the 3 places, we'd have
But we don't.
The first digit can't be a 0, meaning we have 9 digits to pick from.
The last digit needs to be even, which gives 5 digits (2, 4, 6, 8, 0).
There is no constraint on the middle digit and so we have 10 choices.
All told, we can make:
And so the probability of arriving at one of the 450 randomly is:
