Solved

Math homework question

Posted on 2016-10-06
5
90 Views
Last Modified: 2016-10-06
My teacher shows this in the class but I dont understand it. Is it ok if experts can explain this question? I donot understand how it calculate the B'? According to my calculation B'={2,4,6,8,12,14,16,18,22,24,26,28,32,34,36,38,42,44,46,48,52,54,56,58,62,64,66,68,72,74,76,78,82,84,86,88,92,94,96,98} but in the book it solves B'=6

screenshot.PNG
0
Comment
Question by:Tommy Anderson
5 Comments
 
LVL 26

Assisted Solution

by:Shaun Kline
Shaun Kline earned 250 total points
ID: 41831869
If I understand the notation being used, B' is the complement of B. So you are correct in that B' is all of the positive integers not divisible by 5 up to and including 100.

However, the solution is using a shorthand approach to solve n ( A intersect B' ) by understanding that this is asking for the number of elements in A that are not in B.

Since you already determined that there are 6 elements in both A and B, then the number of elements that are just in A is 33 - 6.
0
 
LVL 33

Expert Comment

by:ste5an
ID: 41831890
How are A' and B' defined?
0
 
LVL 27

Accepted Solution

by:
d-glitch earned 250 total points
ID: 41831901
I am afraid you are missing quite a lot:

A = { 3, 6, 9, ... , 99)    
A' = { 1, 2, 4, 5, 7, ... 100}  <== everything that is not in A

B =  {5, 10, 15, ... 100}
B' = { 1, 2, 3, 4, 6, 7, ... 99}  <== everything that is not in B

n( B) = 20  <== The number of elements in B not the elements themselves.
n( B') = 80  ==>  The number of elements in U minus the number of elements in B

Your answer   B' = { 2, 4, 6, 8, 12, ... , 98}  does not make sense for this problem.
There is now mention of even (or odd) numbers.
0
 

Author Comment

by:Tommy Anderson
ID: 41832215
Thanks guys and d-glitch. I just want to ask one more thing, is it OK to post book examples with page numbers if I am not be able to understand it or my teacher work if there is something in the steps I need help?
0

Featured Post

ScreenConnect 6.0 Free Trial

Check out the updates in one game-changing release, ScreenConnect 6.0, based on partner feedback. New features include a redesigned UI that improves session organization and overall user experience. See the enhancements for yourself!

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

How to Win a Jar of Candy Corn: A Scientific Approach! I love mathematics. If you love mathematics also, you may enjoy this tip on how to use math to win your own jar of candy corn and to impress your friends. As I said, I love math, but I gu…
Article by: Nadia
Linear search (searching each index in an array one by one) works almost everywhere but it is not optimal in many cases. Let's assume, we have a book which has 42949672960 pages. We also have a table of contents. Now we want to read the content on p…
This is a video describing the growing solar energy use in Utah. This is a topic that greatly interests me and so I decided to produce a video about it.
Finds all prime numbers in a range requested and places them in a public primes() array. I've demostrated a template size of 30 (2 * 3 * 5) but larger templates can be built such 210  (2 * 3 * 5 * 7) or 2310  (2 * 3 * 5 * 7 * 11). The larger templa…

803 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question