There is only 1 right combination, but possible combinations, so the probability in question is:
A small combination lock has 3 wheels, each labeled with the 10 digits from 0-9. If an opening combination is a particular sequence of 3 digits with no repeats, what is the probability of a person guessing the right combination.
The answer in the back of my book says 1/P 10,3 = .0014
How did they get that I keep getting 720 when I permutaation 10P3.. what do I do