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iwillcrackgmat
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A group of 4th graders and 5th graders is going on a field t 18 Mar 2012, 20:31
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C
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45% (medium)

Question Stats:

73% (02:02) correct 27% (02:24) wrong based on 368 sessions

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A group of 4th graders and 5th graders is going on a field trip to the zoo. Only 20% of the students remembered to bring written permission from their parents. If 40% of the students are 4th graders and 25% if the 4th graders remembered to bring written permission, what percentage of the students are 5th graders who forgot to bring written permission?

A. 10%
B. 30%
C. 50%
D. 60%
E. 80%
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C
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A group of 4th graders and 5th graders is going on a field t 18 Mar 2012, 21:48
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Assume that the total number of students is 100.
=> 20 students got permission from their parents, 40 students are 4th graders, and 10 of the 4th graders got permission from their parents
=> 30 of the 5th graders got written permission
=> 30 of the 5th graders did not get written permission (there are 60 students who are 5th graders)
=> 50% of the 5th graders didn't get permission

Option (C)
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A group of 4th graders and 5th graders is going on a field t 18 Mar 2012, 22:05
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Confused when I saw it for the first time
nice explantion.. really helpful..
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A group of 4th graders and 5th graders is going on a field t 11 Aug 2013, 18:38
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GyanOne
Assume that the total number of students is 100.
=> 20 students got permission from their parents, 40 students are 4th graders, and 10 of the 4th graders got permission from their parents
=> 30 of the 5th graders got written permission
=> 30 of the 5th graders did not get written permission (there are 60 students who are 5th graders)
=> 50% of the 5th graders didn't get permission

Option (C)
Show more


This cant be true.

If you assume total of 100 students, we are given that only 20% have the written permission.
This means only 20 students have the written permission from parents.

Of the 20 students with permission 10 (25%) are 4th graders, which means there are only 10 students left.

So 10 students are 5th graders who have permission.
Where do you get 30 5th graders from?
30 5th graders is basically 50% of 5th graders out of 100 you are assuming, which we are not told.. so..????

Any comments?
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A group of 4th graders and 5th graders is going on a field t 11 Aug 2013, 22:25
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jjack0310
GyanOne
Assume that the total number of students is 100.
=> 20 students got permission from their parents, 40 students are 4th graders, and 10 of the 4th graders got permission from their parents
=> 30 of the 5th graders got written permission
=> 30 of the 5th graders did not get written permission (there are 60 students who are 5th graders)
=> 50% of the 5th graders didn't get permission

Option (C)


This cant be true.

If you assume total of 100 students, we are given that only 20% have the written permission.
This means only 20 students have the written permission from parents.

Of the 20 students with permission 10 (25%) are 4th graders, which means there are only 10 students left.

So 10 students are 5th graders who have permission.
Where do you get 30 5th graders from?
30 5th graders is basically 50% of 5th graders out of 100 you are assuming, which we are not told.. so..????

Any comments?
Show more

You are right. 10 students are 5th graders with permission and 50 are 5th graders without permission.

Now focus on the question: "what percentage of the students are 5th graders who forgot to bring written permission?"

Basically it says that 5th graders who forgot to bring written permission form what % of the TOTAL students?

Since there 50 5th graders who forgot to bring written permission and total students are assumed to be 100, the required % is 50.

Answer is C
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A group of 4th graders and 5th graders is going on a field t 12 Aug 2013, 05:46
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iwillcrackgmat
A group of 4th graders and 5th graders is going on a field trip to the zoo. Only 20% of the students remembered to bring written permission from their parents. If 40% of the students are 4th graders and 25% if the 4th graders remembered to bring written permission, what percentage of the students are 5th graders who forgot to bring written permission?

A. 10%
B. 30%
C. 50%
D. 60%
E. 80%
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.............
diagram describes all ....
Thanks everyone
Attachments

students.png
students.png [ 27 KiB | Viewed 6330 times ]

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A group of 4th graders and 5th graders is going on a field t 02 Mar 2026, 09:09
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Deconstructing the Question

20% of all students brought permission, so 80% forgot.
40% are 4th graders, so 60% are 5th graders.
25% of the 4th graders brought permission.
We need the percentage of all students who are 5th graders who forgot.

Step-by-step

Assume there are 100 students.

Students who brought permission:
\(0.20 \times 100 = 20\)

Number of 4th graders:
\(0.40 \times 100 = 40\)

4th graders who brought permission:
\(0.25 \times 40 = 10\)

So 5th graders who brought permission:
\(20 - 10 = 10\)

Total 5th graders:
\(60\)

5th graders who forgot permission:
\(60 - 10 = 50\)

Answer: 50%
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