Answer:
(6)(5)(4) = 120
Explanation:
For a permutation, order matters. The equation for a permutation is (n!) / (n-k)! where n represents the total number of items you have to choose from and k represents the amount of items taken into account. Therefore we have
6! / (6-3)! = 6!/3! =(6)(5)(4)(3)(2)(1)/(3)(2)(1) = (6)(5)(4) = 120
Here is another way to picture it:
In this case, we have 6 different dessert options to choose from. Let's say the desserts are A, B, C, D, E, and F
1st favorite (6 choices): A, B, C, D, E, and F. Let's say A is the 1st favorite
2nd favorite (5 choices): B, C, D, E, and F. Let's say B is the 2nd favorite
3rd favorite (4 choices): C, D, E, and F. Let's say C is the 3rd favorite
As you can see we actually have 6! choices for the numerator, but we are only choosing to 3 places, so we don't need the rest of the numbers, which can be represented by 3!
Therefore we have: 6! / (6-3)! = 6!/3! =(6)(5)(4)(3)(2)(1)/(3)(2)(1) = (6)(5)(4) = 120