Permutation/Principle of counting

Question

Secretary/manager assignments--From a pool of 7 secretaries, 3 are selected to be assigned to 3 managers, 1 secretary to each manager. In how many ways can this be done?

Answer 1

This is a permutation problem (order matters): 7P3 is the answer (you finish the evaluation).

Formula: nPr = n! / (n-r)!

The exclamation mark means "factorial"

The answer is 7 times 6 times 5 = 210

 

To find out more about permutations, I suggest that you Google that word, because apparently your class has not covered that.

 

The 7•6•5 solution I give can be arrived at without the Permutation formula, just reasoning as follows: For the first manager, there are 7 possible secretaries; ;then for second mgr, 6 choices, & finally 5 choices for sec for 3rd mgr.

 

Thanks for asking!