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percentage sets

by shilpi84 » Wed Jun 24, 2009 12:38 am
At a certain conference, 72% of the attendees registered at least
two weeks in advance and paid their conference fee in full. If
10% of the attendees who paid their conference fee in full did
not register at least two weeks in advance, what percent of
conference attendees registered at least two weeks in
advance?

(A) 18.0%
(B) 62.0%
(C) 79.2%
(D) 80.0%
(E) 82.0%

OA:D
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by Robinmrtha » Wed Jun 24, 2009 9:09 am
Let 100 be the number of participants

Then draw the table...
Total Reg and who have paid the full amount = 72
Total full paid x
Total full paid but late registered x - 72

Reg Late Reg Total
Full pay 72 x-72 x

By question late reg and full pay =10 percent of x

So,
x-72= 10 percent of x
Therefore x= 80

Ans D
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by shilpi84 » Wed Jun 24, 2009 6:54 pm
Robinmrtha wrote:Let 100 be the number of participants

Then draw the table...
Total Reg and who have paid the full amount = 72
Total full paid x
Total full paid but late registered x - 72

Reg Late Reg Total
Full pay 72 x-72 x

By question late reg and full pay =10 percent of x

So,
x-72= 10 percent of x
Therefore x= 80

Ans D
The question asks what percent of
conference attendees registered at least two weeks in
advance?
x are the people who paid full fees but that also includes people who registered 2 weeks in advance and also who did not register 2 weeks in advance.
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by shilpi84 » Wed Jun 24, 2009 10:42 pm
some1 please explain! :?
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by tohellandback » Thu Jun 25, 2009 12:29 am
check the image

now the equation is 0.1x+72=x
0.9x=72
x=80 percent
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The powers of two are bloody impolite!!
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by ghacker » Thu Jun 25, 2009 9:03 am
At a certain conference, 72% of the attendees registered at least
two weeks in advance and paid their conference fee in full. If
10% of the attendees who paid their conference fee in full did
not register at least two weeks in advance, what percent of
conference attendees registered at least two weeks in
advance?

If you read the stimulus carefully you get the answer with out much fuzz
( red and Blue parts)


Answer is 80%
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by Morgoth » Thu Jun 25, 2009 1:29 pm
I think the question is incorrect or at least the last part is incorrect.

The above venn diagram by tohellandback incorrectly calculated on the statement that
"If 10% of the attendees who paid their conference fee in full did
not register at least two weeks in advance"

The full part should be taken as x not the at least 2 weeks part.

Here are my calculations:

Image


Let the total attendes be 100, 72% of the attendees registered at least
two weeks in advance and paid their conference fee in full.

Let people who paid in full be x, 10% of the attendees who paid their conference fee in full did not register at least two weeks in advance

Therefore, 10%x did not register 2 weeks in advance but paid in full.

Hence, we can only find out how many people actually paid in full.

x = 10%x + 72

.9x = 72

x = 80


Please let me know what you guys think about this or is there something that I am completely oblivious about.

Thanks.
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by tohellandback » Thu Jun 25, 2009 5:57 pm
Morgoth wrote:I think the question is incorrect or at least the last part is incorrect.

The above venn diagram by tohellandback incorrectly calculated on the statement that
"If 10% of the attendees who paid their conference fee in full did
not register at least two weeks in advance"

The full part should be taken as x not the at least 2 weeks part.

Here are my calculations:

Image




Let the total attendes be 100, 72% of the attendees registered at least
two weeks in advance and paid their conference fee in full.

Let people who paid in full be x, 10% of the attendees who paid their conference fee in full did not register at least two weeks in advance

Therefore, 10%x did not register 2 weeks in advance but paid in full.

Hence, we can only find out how many people actually paid in full.

x = 10%x + 72

.9x = 72

x = 80


Please let me know what you guys think about this or is there something that I am completely oblivious about.

Thanks.
Morgoth,
I think my calculation is right. Now ur calculation is right too but your assumption is wrong..

question says "10% of the attendees who paid their conference fee in full did
not register at least two weeks in advance"

that doesn't mean what you have said Therefore, 10%x did not register 2 weeks in advance but paid in full."

that means exactly exactly what the question says. 10 percents of the people who paid their conference fee in full did
not register at least two weeks in advance

the X you have found is the the percentage of people who paid in full.
this is what your x is "Let people who paid in full be x". isn't it?
but question asks otherwise.
The powers of two are bloody impolite!!
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