I don't think I'm figuring this question out correctly...

C

cabecrandall

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Nov 14, 2013
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Here's the question:
One hundred fifteen students could sign up to hear three different speakers for career day. Seventy students hear the nurse speak, 37 heard the firefighter, and 63 heard the webmaster. Some students heard more than one speaker. The results are shown in the table:

Number of Students. . .Speaker
. . . . .15. . . . . . . . . .All three
. . . . .20. . . . . . . . . .nurse and firefighter
. . . . .30. . . . . . . . . .webmaster and nurse
. . . . .12. . . . . . . . . .firefighter only

How many students signed up only for webmaster?

Now, what I first did was subtract all of the people that did more than one from the original amount of students (i.e subtracted 20 for the nurse) with the table, and eventually got 18 as my answer, though my teacher said specifically in class that the answer was over 20, so I'm confused, you guys know any good methods of doing this problem?

P.S. This is a bonus question, I just really want to know how to do things like it for the future.
Thanks, cabecrandall :wink:
 
Last edited by a moderator:
cabecrandall said:
One hundred fifteen students could sign up to hear three different speakers for career day. Seventy students hear the nurse speak, 37 heard the firefighter, and 63 heard the webmaster. Some students heard more than one speaker. The results are shown in the table:

Number of Students. . .Speaker
. . . . .15. . . . . . . . . .All three
. . . . .20. . . . . . . . . .nurse and firefighter
. . . . .30. . . . . . . . . .webmaster and nurse
. . . . .12. . . . . . . . . .firefighter only

How many students signed up only for webmaster?
Click to expand...
Have you ever worked with Venn diagrams? I suspect that you're expected to use that method for this. ;)
 
stapel said:
Have you ever worked with Venn diagrams? I suspect that you're expected to use that method for this. ;)
Click to expand...

I tried, this question is rather off from what we have been learning (slopes, y=mx form, etc.) but I just can't grasp each number with the Venn Diagrams, I've done these a couple times before, but I can't remember how I did it with Venn Diagrams, though I remember I did. Any help?
 
cabecrandall said:
I tried,...but I just can't grasp each number with the Venn Diagrams, I've done these a couple times before, but I can't remember how I did it....
Click to expand...
Did the Venn-diagram lesson (in the link provided in my previous reply) help at all? ;)
 
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