We know that a box contains n different objects. We will remove three objects from the box one at a time, and we will not put the previous object back. We want to find the number of possible outcomes of this experiment. To do so let's write the number of possible outcomes each time we pick an object.
First Removal
Second Removal
Third Removal
Number of Objects
n
n-1
n-2
Number of Possible Outcome
n
n-1
n-2
Notice that we did not put the objects back into the box, so after picking an object the number of objects in the box reduces by one in each stage. Now we will use the Fundamental Counting Principle to find the number possible outcomes.
