This question already has an answer here:
5 persons own a safe with a number of locks (arranged parallel, i.e. all locks must be opened to open the safe). One lock can have any number of keys. The owners want any combination of (a minimum of) 3 persons to be able to open the safe.
I can see that one solution is to have 5!/(3!2!)=10 locks and distribute the keys according to the permutations owners. But is that also the minimum number of locks?
Edit: following new searches using the work "lock" I see that the question might be a duplicate. I see also that my own solution may be wrong according to a comment