probality of combination lock HELP!!

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

Re: probality of combination lock HELP!!

There is only 1 right combination, but possible combinations, so the probability in question is:

Re: probality of combination lock HELP!!

Thank you so much I didn't round that was my issue.. been at it for a while and you cleared it up good post

Re: probality of combination lock HELP!!

Yes, you did it correctly, so I wanted to show another approach, and at the same time *imply* that rounding was the only issue. :)