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# In a certain school, there are 80 Freshmen, 100 Sophomores, and 220 Up

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Magoosh GMAT Instructor
Joined: 28 Dec 2011
Posts: 4668
In a certain school, there are 80 Freshmen, 100 Sophomores, and 220 Up [#permalink]

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20 Oct 2014, 11:50
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(N/A)

Question Stats:

79% (02:16) correct 21% (03:08) wrong based on 131 sessions

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In a certain school, there are 80 Freshmen, 100 Sophomores, and 220 Upperclassmen, drawn from three cities: A, B, and C. Sixty percent of students are from A, 30% from B, the rest from C, and all these students from C are freshmen. Half the student from B are upperclassman, and the rest are split evenly between the other two grades. How many sophomores are from A?
(A) 60
(B) 70
(C) 80
(D) 90
(E) 100

For a discussion of the Double Matrix method for solving questions of this sort, as well as the OE for this question, see:
https://magoosh.com/gmat/2014/gmat-prac ... lems-sets/

Mike

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SVP
Status: The Best Or Nothing
Joined: 27 Dec 2012
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Location: India
Concentration: General Management, Technology
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In a certain school, there are 80 Freshmen, 100 Sophomores, and 220 Up [#permalink]

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20 Oct 2014, 21:09
2

Solved using matrix method as below:

Attachment:

mat.png [ 6.72 KiB | Viewed 1913 times ]

1. Total Freshmen = 80

2. Total Sophomores = 100

3. Total Upperclassmen = 220

4. Net people = 80+100+220 = 400

5. 60% from A $$= \frac{60}{100} * 400 = 240$$

6. 30% from B $$= \frac{30}{100} * 400 = 120$$

7. Remaining from C = 400 - (240+120) = 40

8. All students of C are Freshmen = 40

9. Half the student from B are upperclassman = 120/2 = 60

10. rest are split evenly between the other two grades = 30

11. rest are split evenly between the other two grades = 30

12. How many sophomores are from A = 100 - 30 = 70
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Manager
Joined: 14 Jul 2014
Posts: 94
Re: In a certain school, there are 80 Freshmen, 100 Sophomores, and 220 Up [#permalink]

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22 Jan 2015, 23:46
1
Ans B = 70

I don't know how to upload the sceenshot but I used 3*3 Matrix

F S U Total
A ? 240
B 30 30 60 120
C 40 0 0 40

Total 80 100 220 400

On solving we get ? = 70
SVP
Status: The Best Or Nothing
Joined: 27 Dec 2012
Posts: 1837
Location: India
Concentration: General Management, Technology
WE: Information Technology (Computer Software)
Re: In a certain school, there are 80 Freshmen, 100 Sophomores, and 220 Up [#permalink]

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23 Jan 2015, 02:30
1
This is a repeated question... have solved it detailed below

in-a-certain-school-there-are-80-freshmen-100-sophomores-and-220-up-187208.html?fl=similar
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Senior Manager
Joined: 24 Oct 2016
Posts: 294
Location: India
Schools: IIMB
GMAT 1: 550 Q42 V28
GPA: 3.96
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Re: In a certain school, there are 80 Freshmen, 100 Sophomores, and 220 Up [#permalink]

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27 Feb 2017, 04:31
the answer should be B we can solve it by suing matrix method .
Re: In a certain school, there are 80 Freshmen, 100 Sophomores, and 220 Up   [#permalink] 27 Feb 2017, 04:31
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