Thinking Mathematically (6th Edition)

Published by Pearson
ISBN 10: 0321867327
ISBN 13: 978-0-32186-732-2

Chapter 2 - Set Theory - 2.5 Survey Problems - Exercise Set 2.5 - Page 103: 27

Answer

The number of elements for the different asked regions is shown below:

Work Step by Step

Simplify region II to get the elements: \[n\left( A\cap B \right)\]is equal to region II\[+\]V. \[\begin{align} & n\left( A\cap B \right)=3 \\ & \text{II}+\text{V}=3 \\ & \text{II}+2=3 \\ & \text{II}=1 \end{align}\] For region IV: \[n\left( A\cap C \right)\]is equal to region IV\[+\]V. \[\begin{align} & n\left( A\cap C \right)=5 \\ & \text{IV}+\text{V}=5 \\ & \text{IV}+2=5 \\ & \text{IV}=3 \end{align}\] For region VI: \[n\left( B\cap C \right)\]is equal to region VI\[+\]V. \[\begin{align} & n\left( B\cap C \right)=3 \\ & \text{VI}+\text{V}=3 \\ & \text{VI}+2=3 \\ & \text{VI}=1 \end{align}\] For region I: \[n\left( A \right)\]is equal to region I\[+\]II\[+\]IV\[+\]V. \[\begin{align} & n\left( A \right)=\text{I}+\text{II}+\text{IV}+\text{V} \\ & 11=1+2+3+\text{I} \\ & \text{I}=11-6 \\ & \text{I}=5 \end{align}\] For region III: \[n\left( B \right)=8\]is equal to region II\[+\]III\[+\]V\[+\]VI. So, \[\begin{align} & \text{II}+\text{III}+\text{V}+\text{VI}=n\left( B \right) \\ & 1+2+1+\text{III}=8 \\ & \text{III}=8-4 \\ & \text{III}=4 \end{align}\] For region VII: \[n\left( C \right)=14\]is equal to region IV\[+\]V\[+\]VI\[+\]VII. \[\begin{align} & \text{IV}+\text{V}+\text{VI}+\text{VII}=n\left( C \right) \\ & 3+2+1+\text{VII}=14 \\ & \text{VII}=14-6 \\ & \text{VII}=8 \end{align}\] For region VIII: \[\begin{align} & \text{VIII}=30-n\left( A\cup B\cup C \right) \\ & =30-\left( 5+1+4+3+2+1+8 \right) \\ & =30-24 \\ & =6 \end{align}\]
Update this answer!

You can help us out by revising, improving and updating this answer.

Update this answer

After you claim an answer you’ll have 24 hours to send in a draft. An editor will review the submission and either publish your submission or provide feedback.