Revision as of 13:02, 3 February 2010

If anyone wants to work on this as a group, I'm willing. I'm struggling some and have class during his office hours. Call/text 317-605-6720. thanks.

HW3MA375S10

5.3 - 20, 22, 24, 32 | 5.4 - 21, 22, 28, 31, 38

I thought it would be nice to have a template for this week's homework so it would be easier to access information about the problems.

I like the template idea. This will be helpful!

Section 5.3

20. Does anyone know how to account for overcount in these problems? Or do you not have to take that into account

a) I'm struggling to get this one. It's not just 3 0's and pick the rest, it's exactly 3 0's. How would that effect the Permutation (or combination)?

Look at example 14 in section 5.3.

22.

24. I keep getting a small number for 24, but I know the answer should be larger. Can anyone help me?

Think about how we distinguished how many of each fruit we stole using dividers. Perhaps you need to take into account the permutations of the men and women.

 After looking at example 7, I decided to divide the men and women into 6 blocks of "WM" and then 4 "W"s. I'm not sure if this works, however. 

Think of it as this |*|*|*|*|*|*|*|*|*|*| the bars are men and star as women. You will have to choose 6 spots among the available ones. Then you also have to consider how you want to place the 10 women, but this is very simple, don't think too much for how to place 10 of them.

32. Any ideas on 32 b?

do we use the form (n!)/(n-r)!*r! on this portion or is it just n!/r! ?

The first form you mentioned is for combinations, and is used to reflect collections of unordered objects. The second form is for permutations, where the objects are ordered. In this case, the order of the letters definitely matters, and so you wish to distinguish between, say, "ABCDEF" and "FEDCBA". So this is a permutation type problem.

Section 5.4

21. Does anybody know how to show part a) without just using math to show that the two sides are equal (which we have to do for b). I'm stuck on how to go about this.

For the left side of the equation first consider the number of subsets you can make, then consider the number of elements you can pick out of any given subset then use product rule. For the right side of the equation, consider the number of elements you can choose, then remove it from the group to get n-1 element set and then consider the number of k-1 element subsets of that set. So you have a chosen element and a k-1 element subset that doesn't include your original pick, hope this helps.

22.

28.

31.

38.

Back to 2010 Spring MA 375 Walther

Does anyone have any idea how the midterm is going to be,the pattern??