5 letters in each of 3 rings of a lock are printed. If the lock can be opened by only one permutation of three letters, then find the number of permutations by which the lock cannot be opened? ps: by locks it meant those locks we have in ourbriefcase
1 Answer
Apr 7, 2018
124 permutations will fail to open the lock.
Explanation:
The total number of possible permutations are
Because only one permutation opens the lock, the remaining 124 do not.
