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gmat paper test code 28 section 5 q11 ( ratio problem)

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by ifthyder » Wed Apr 30, 2008 2:34 am
In certain calculus class, the ratio of the number of mathematics majors to the number of students who are not mathematics majors is 2 to 3. if 2 more mathematics majors were to enter the class , the ratio would be 1 to 2, How many students in the class ?

A)10
B)12
C)21
D)28
E)35
answer is 28 .
but doubt is the this question is correct. How come mba.com's copywrite practice material of cost of 25$ turn out to be wrong. please confirm it whether it is wrong or not ?

my stragedy to solve is below

2X+2/3X=1/2
4X+4=3X
-ve value of X how come ?


a
Last edited by ifthyder on Wed Apr 30, 2008 10:30 pm, edited 2 times in total.
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by codesnooker » Wed Apr 30, 2008 9:40 pm
Dude this question 100% incorrect (If you have posted here correctly).

It initially states that the ratio of Math to Non-Math is 2:3 i.e Out of every five students there are 2 math students = 40% strength is of Math students.

Now if we add two more Math student in the class the new ratio would be 1:2 i.e. out of every 3 student there are 1 math student. It means new math student's strength = 33.33%

How can be the percentage of math student would reduced on adding students in math section.

So, this question is 100% incorrect. BTW From which source did you pick this question???
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by rey.fernandez » Wed Apr 30, 2008 11:00 pm
I agree that it's a flawed question. Not only does your equation yield a negative number, but also if the answer really is 28, the number of math majors would not be a whole number.

Ask for a refund?

Rey
Rey Fernandez
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by pengstrom » Mon Feb 16, 2009 12:37 am
It is correct:

Look at it this way:

2 to 5 = 7
4 & 10 = 14
6 & 15 = 21
8 & 20 equal 28 --> add 2 and you have 10 & 20, or 1 to 2.
10 & 24 equal 35

Source is the official study material sent out by GMAT, test code 28.
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by sureshbala » Mon Feb 16, 2009 2:40 am
If the initial ratio of math and science is 2:5, then this is correct. Please check the question once again
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by LifetimesofSC » Tue Jun 09, 2009 8:45 am
In a certain calculus class, the ratio of the number of mathematics majors to the number of students who are not mathematics majors is 2 to 5. If 2 more mathematics majors were to enter the class, the ratio would be 1 to 2. How many students are in the class?

a- 10
b- 12
c- 21
d- 28
e- 35

Answer D
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by Nikos » Sun Apr 22, 2012 6:23 am
majors/no majors 2/5 become 1/2
homonyms: 4/10 5/10
multiply by 2: 8/20 10/20
Difference between numerators is 2
Therefore 8+20=28 Answer is D.
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