# Thread: Perms and Combs help please

1. ## Perms and Combs help please

Can someone please help me out! I have a test tomorrow and i'm trying to get as much review as I can... I'm stuck on this problem though:

So Sandra's fav dishes are:

Meat Dishes
Salads
Deserts

The number of recipes for the meat dishes are 4, the # of recipes for salads are 2, and the # of recipes for deserts are 3...

She's been invited to go to 4 parties and she's going to make one of these dishes for each of hte parties..

A) If Sandra wants to make a different dish for each party, how many ways could she take something different to each of the four parties?

I'm not sure but I think the answer is 288 or 4! x 2! x 3!

B) If Sandra doesn't mind repeats, how many ways could she take something to each of the four parties?

Again i'm not sure, but would it be 9C4 ?

C) Sandra is taking her favorite dish of meatballs to the first party, how many ways can she take something different to each of the 4 parties?

Not sure exactly how you do this one but I know it's permutations.

D) Sandra wants to take meaballs to the first party, and wants to bring pasta salad to the last party. How many wayscan she take something different to each of the 4 parties?

Again not sure, I know it's permutations but don't know how to solve it.

E) What is the probability that she takes at least 12 meat dish to the parties?

n (s) / n (o) = 4/ 288?

Thanks, I'm really having trouble with this unit.... I have a test tomorrow so if someone can look over this and tell me what's right and what's wrong and how I can improve it and get the right answer, then thanks so much.

2. Well to show that I actually tried this problem... can someone please tell me if these updated answers are right? I'm not sure, but i think i figured it out.

A) 9P4 (9 recipes, 4 parties)

B) 9^4 (9 x 9 x 9 x 9 .... due to 9 recipies and 4 parties)

C) 8P3 (8 Recipies, 3 parties since Metballs is added to first party)

D) 7P2 (7 Recipies, 2 parties since Meatballs and Pasta Salad are added to the 1st and last respectivlely)...

E) still not sure...

Can someone please tell me if this is right or wrong?