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# In a school there are two sections A and B. When a few students from

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Intern
Joined: 24 Mar 2018
Posts: 7
In a school there are two sections A and B. When a few students from  [#permalink]

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11 Apr 2018, 08:43
4
00:00

Difficulty:

65% (hard)

Question Stats:

40% (02:48) correct 60% (03:37) wrong based on 16 sessions

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In a school there are two sections A and B. When a few students from section B took transfer to section A the strength of section A increased by 22.5% and strength of B decreased by 30%. Now, what percentage of students in section A should be given a transfer to section B such that section A and section B have the same strengths?
A) $$\frac{100}{7}$$%
B) 20%
C) $$\frac{200}{7}$$%
D) 40%
E) $$\frac{300}{7}$$%
Math Expert
Joined: 02 Aug 2009
Posts: 7415
In a school there are two sections A and B. When a few students from  [#permalink]

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11 Apr 2018, 09:13
2
hetmavani wrote:
In a school there are two sections A and B. When a few students from section B took transfer to section A the strength of section A increased by 22.5% and strength of B decreased by 30%. Now, what percentage of students in section A should be given a transfer to section B such that section A and section B have the same strengths?
A) $$\frac{100}{7}$$%
B) 20%
C) $$\frac{200}{7}$$%
D) 40%
E) $$\frac{300}{7}$$%

so 22.5% of A = 30% of B......
$$22.5*A = 30*B.......A = \frac{30B}{22.5} = \frac{4B}{3}$$..

Now let B = 300, so A = 400..
30% of 300 = 90..
so present strength - $$A= 400+90=490$$ and $$B = 300-90=210$$..

to equalize both should have $$\frac{300+400}{2}=350$$

so $$490-350 = 140$$ should move to B from A..
$$% = \frac{140}{490}*100 = \frac{200}{7}$$

C
_________________

1) Absolute modulus : http://gmatclub.com/forum/absolute-modulus-a-better-understanding-210849.html#p1622372
2)Combination of similar and dissimilar things : http://gmatclub.com/forum/topic215915.html
3) effects of arithmetic operations : https://gmatclub.com/forum/effects-of-arithmetic-operations-on-fractions-269413.html
4) Base while finding % increase and % decrease : https://gmatclub.com/forum/percentage-increase-decrease-what-should-be-the-denominator-287528.html

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In a school there are two sections A and B. When a few students from   [#permalink] 11 Apr 2018, 09:13
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