10. The number lock of a suitcase has wheels, each labelled with ten digits, i.e., from to . The lock opens with a sequence of four digits with no repeats. What is the probability of a person getting the right sequence to open the suitcase?
Given that each wheel can be labelled with 10 digits,.
The number of ways of selecting 4 different digits out of the 10 digits =
These 4 digits can be arranged in their own ways.
Number of four-digit numbers without repetitions =
The number of combination that can open the suitcase = 1
Required probability of getting the right sequence to open the suitcase =