query 4

course Mth 151

稊£ÜüwöÆ~±K̦GÓÅm”¬·­S¼„assignment #004

004. `Query 4

College Algebra

02-05-2009

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18:42:04

2.4.12 n(A') = 25, n(B) = 28, n(A' U B') = 40, n(A ^ B) = 10

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RESPONSE -->

I. 10

II. 0

III. 33

IV. 40

confidence assessment: 2

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18:50:04

** 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 -->

I thought A ^ B =10 so I put that in the first region. I then subtracted 10 from 28 which was B and entered 18 in the third region. Since A' means everything but A I put 15 in the third one too because 25-10 =15 and lastly In the fourth region I put 40 because (A' U B') is everything but A and B so I thought it would go there. I see I was somewhat right in my thinking but not quite there. I see I should have subtracted the B's 18 from A's 25. It is kind of confusing with or with out the primes.

self critique assessment: 2

For example, with (A' U B'), you ask the following questions in order:

What regions are in A?

What regions are therefore in A'?

What regions are in B?

What regions are therefore in B'?

So, what regions are in A' U B'?

If you can break it down to one question at a time, you can figure out just about anything.

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18:53:33

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

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RESPONSE -->

I think you are off one in these questions. Last question should have been #13 and this one #19. This would help with the confusion of what we are supposed to do with the problem.

He wrote three.

confidence assessment: 3

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18:54:25

** 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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RESPONSE -->

I agree

self critique assessment: 3

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19:21:01

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 ......!!!!!!!!...................................

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RESPONSE -->

I assume you are asking the same questions as the book.

Fat =37 b/c it said there are 37 fat chickens and when adding 9 fat red roosters, 2 fat red hens, and 26 fat roosters this comes to be 37.

Red = 22 b/c there are 9 fat red roosters, 2 fat red hens, 6 thin red roosters, and 5 red hens coming to 22.

Male= 50 b/c there are 26 fat roosters, 18 thin brown roosters, and 6 thin red roosters.

Fat but not Male=11 b/c there are 37 fat chickens and when you subtract 26 fat roosters that comes to be 11.

Brown but not fat=25 b/c there are 18 thin brown roosters and 7 thin brown hens equaling to 25.

Red and Fat=11 b/c there are 9 fat red roosters and 2 fat red hens which is 11.

confidence assessment: 3

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19:22:04

** 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 agree

self critique assessment: 3

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&#This looks very good. Let me know if you have any questions. &#