What is the probability of a second digit of a locker combination is less than 7 if the first digit is less than 7 and cannot be repeated?

Answer 1

Assuming a zero is one of the allowed possibilities, then there are 7 numbers less than 7 (ie., 0-6). However, since you are not allowed to repeat, then that leaves 6 possibilities out of a presumed total of 10. If you want it in percentage, that would be a 60% chance, since percent really means "per 100," and 6 out of 10 is the same as 60 out of 100. So if you mean this 2nd digit by itself and just its odds, it should be 60%.

Now, if you mean the chances of the first 2 digits together, then one would have to multiply the possibilities of each event. There is a 70% chance of finding a digit less than 7, assuming 0 is allowed. And there is a 60% chance of finding a digit less than 7 that does not repeat the previous. So if you multiply 7 out of 10 with 6 out of 10, you get 42 out of 100, or 42%.