Assi 3

course Mth 151

22:33:55`q001. Note that there are 5 questions in this assignment.

Again we have a total of 35 people in a room. Of these, 20 have dark hair and 15 have bright eyes. There are 8 people with dark hair and bright eyes.

Let A stand for the collection of people who have dark hair and B for the collection who have bright eyes. The Intersection of these two collections is denoted A ^ B, and stands for the collection of all people who have both dark hair and bright eyes. The Union of these two collections is denoted A U B, and stands for the collection of all people who have at least one of these characteristics.

In terms of the diagram you made for the preceding problem, describe the collection A ^ B and the collection A U B. Give the number of people in each of these collections (these numbers are designated by the notation n ( A ^ B) and n(A U B) ). Refer to the diagrams you have made.

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

RESPONSE -->

I have In diagram

A= {20 dark hair people}

B={15 bright eye people}

A^B={8 dark hair people and bright eye people}

A U B= ( 12 dark hair people} U {7 dark eye people}

A^B =n(8)

A U B=n(12) U n(7) = n(19)

confidence assessment: 2

.................................................

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

22:36:04

The collection A ^ B consists of all the people with both dark hair and bright eyes, which corresponds to the overlap between the two circles (region I). There are 8 people in this overlap, so we say n(A ^ B) = 8.

The collection A U B consists of all the people who have least one of the characteristics. This would include the 12 people with dark hair but not bright eyes, located in the first circle but outside the overlap (region II); plus the 7 people with bright eyes but not dark hair, located in the second circle but outside the overlap (region III); plus the 8 people with both characteristics, located in the overlap (region I). Thus we include the 12 + 8 + 7 = 27 people who might be located anywhere within the two circles.

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

RESPONSE -->

I did not counted the 8 people with both characteristics, only subtracted them form regions II and III.

self critique assessment: 3

.................................................

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

22:41:53

`q002. Continuing the preceding example, we let A' stand for the people who are not in the collection A, and we let B' stand for the people who are not in the collection B.

What are the characteristics of the people in A', and what characterizes people in B' ? What are n(A ') and n(B '), the numbers of people in A' and B' ?

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

RESPONSE -->

n(A')= {bright eye people}

n(B')= {dark hair people}

the numbers are:

n(A')= n{7}

n(B')= n{12}

confidence assessment: 3

.................................................

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

22:44:37

Of the 35 people, those in A' are those outside of A. Since A consists of all the dark-haired people, A' consists of all the people lacking dark hair. This includes the 8 people outside of both circles (people having neither dark hair nor bright eyes, region IV) and the 7 people in the second circle but outside the overlap (people having bright eyes but not dark hair, region III). n(A ' ) is therefore 8 + 7 = 15.

Since B consists of all the bright-eyed people, B' consists of all the people lacking bright eyes. This would include the 8 people outside both circles (region IV), all of whom lack both dark hair and bright eyes, and the 12 people in the first circle but outside the overlap (region II), who have dark hair but not bright eyes. n ( B ' ) is therefore 12 + 8 = 20.

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

RESPONSE -->

I had understood that the people in the intersection HAD BOTH CHARACTERISTICS, that's why I left them out when giving the numbers for A' and B'

self critique assessment: 3

It's appropriate to leave these intersections out.

However the complement of A includes everyone in B who isn't in the intersection, as well as everyone who isn't in either of the sets (i.e., who has neither dark hair nor bright eyes.

.................................................

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

22:51:59

`q003. ( A U B ) ' stands for the everyone outside A U B, and ( A ^ B ) ' stands for everyone outside A ^ B. What characterizes the people in each of these collections, and how many people are there in each?

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

RESPONSE -->

(A U B)'=n(dark hair) nor n(bright eyes)

n(12)+ n(7)+n(8)= 27

confidence assessment: 1

.................................................

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

22:59:39

A U B consists of everyone having at least one of the characteristics (dark hair, bright eyes), and is represented by the numbers in the two circles (regions I, II, III). ( A U B ) ' consists of the people who do not have at least one of the characteristics, and is represented by the number outside both circles (region IV). This number is 8, representing the 8 people who have neither dark hair nor bright eyes.

A ^ B stands for all the people with both of the two characteristics (represented by the overlap, region I), so ( A ^ B ) ' stands for all the people who do not have both of the two characteristics (represented by everything outside region I, or regions II, III and IV). [ Note that (A ^ B)' is not the same as the collection of people who have neither characteristic. Anyone who does not have both characteristics will be in ( A ^ B ) ' . ] ( A ^ B )' must include those who have neither characteristic, and also those who have only one of the characteristics.

The 8 people outside both circles, the 12 people in the first circle but outside the overlap, and the 7 people in the second circle but outside the overlap all lack at least one characteristic to, so these 8 + 12 + 7 = 27 people make up( A ^ B ) '.

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

RESPONSE -->

so if A U B=everyone with at least one charac.

(A U B)' =8 becuase they have none of the characteristics

A^B= everybody with both charac.

(A^B)'= everyone who do not have both charac. and should be the number on region IV

self critique assessment: 3

................................................."

&#Good responses. See my notes and let me know if you have questions. &#