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I realize that my answers don't allow for much for seeing examples of my work. But I feel comportable with working with Venn diagrhams

цᐜassignment #004

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004. `Query 4

College Algebra

09-23-2007

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15:03:46

2.4.13 (formerly 2.4.12) This was not assigned but you answered similar questions and should be able to answer this one: n(A') = 25, n(B) = 28, n(A' U B') = 40, n(A ^ B) = 10. What is n(A - B)?

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RESPONSE -->

I feel comfortable with working similar questions, the problem i am having is understanting n(A^b)=10

confidence assessment: 0

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15:08:18

** In terms of the picture (2 circles, linked, representing the two sets) there are 28 in B and 10 in A ^ B so there are 18 in the region of B outside of A--this is the region B-A.

There are 25 outside of A, and 18 of these are accounted for in this region of B. Everything else outside of A must therefore also be outside of B, so there are 25-18=7 elements in the region outside of both A and B.

A ' U B ' consists of everything that is either outside of A or outside of B, or both. The only region that's not part of A ' U B ' is therefore the intersection A ^ B, since everything in this region is inside both sets.

A' U B' is therefore everything but the region A ^ B which is common to both A and B. This includes the 18 elements in B that aren't in A and the 7 outside both A and B. This leaves 40 - 18 - 7 = 15 in the region of A that doesn't include any of B. This region is the region A - B you are looking for. **

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RESPONSE -->

okay

self critique assessment: 0

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When you do not answer a question you need to continue in your self-critique with a phrase-by-phrase analysis of the solution, detailing everything you do and do not understand. Specific questions are encouraged if you do not understand everything.

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15:13:26

query 2.4.18 wrote and produced 2, wrote 5, produced 7 &&&& How many did he write but not produce?

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He wrote 3.

using a Venn Diagrams. I drew two circles, Leting 10 be the universe, and letting 2 be A and B intersection.Levaing 3 for which was writen, and 5 for produce.

confidence assessment: 2

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15:13:47

** You need to count the two he wrote and produced among those he wrote, and also among those he produced.

He only wrote 5, two of which he also produced. So he wrote only 3 without producing them.

In terms of the circles you might have a set A with 5 elements (representing what he wrote), B with 7 elements (representing what he produced) and A ^ B with 2 elements. This leaves 3 elements in the single region A - B and 5 elements in the single region B - A. The 3 elements in B - A would be the answer to the question. **

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self critique assessment:

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15:16:54

2.4.25 (formerly 2.4.24) 9 fat red r, 18 thn brown r, 2 fat red h, 6 thin red r, 26 fat r, 5 thin red h, 37 fat, 7 thin brown hens. ......!!!!!!!!...................................

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I'm sorry i didn't understand the question

confidence assessment: 1

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15:18:30

** Here's my solution. Tell me if there is anything you disagree with (I'm not infallible) or don't understand.

incidental: 18 thin brown roosters, 7 thin brown hens, 6 thin red hens and the 6 thin roosters which aren't fat (out of the 50-26=24 thin roosters 18 are brown so 6 are red) adds up to 37 thin chickens

How many chickens are fat?

37 as given

How many chickens are red?

22: 9 fat red roosters, 6 thin red roosters, 5 thin red hens, 2 fat red hens.

How many chickens are male?

50: 9 fat red roosters are counted among the 26 fat roosters so the remaining 17 fat roosters are brown; then there are 18 thin brown roosters and 6 thin red roosters; the number of roosters therefore adds up to 9 + 18 + 6 + 17 = 50

How many chickens are fat not male?

26 of the 37 fat chickens are male, leaving 11 female

How many chickens are brown not fat?

25: 18 thin brown roosters, 7 thin brown hens adds up to 25 thin brown chickens

How many chickens are red and fat?

11: 9 fat red roosters and 2 fat red hens.**

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RESPONSE -->

I understand now, you were asking for the solution to the question of how many in each element.

self critique assessment: 1

As I've mentioned before, you need to go by the statement of the problem as it is given in the text.

Also note that the q_a_ has been updated to accomodate changes in some problem numbers. Be sure you are using the updated version.

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See my notes about self-critique.

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I suggest that you copy this document into Notepad, insert self-critiques after the given solution on those problems where your solution differed from the given solution, and submit the resulting document so I can help you address anything you might not be clear on.

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