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# There are two examinations rooms A and B. If 10 students are sent from

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There are two examinations rooms A and B. If 10 students are sent from  [#permalink]

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08 Apr 2019, 23:03
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Difficulty:

45% (medium)

Question Stats:

65% (02:19) correct 35% (02:25) wrong based on 52 sessions

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There are two examinations rooms A and B. If 10 students are sent from A to B, then the number of students in each room is the same. If 20 candidates are sent from B to A, then the number of students in A is double the number of students in B. The number of students in room A is

a. 20

b. 80

c. 100

d. 150

e. 200

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Re: There are two examinations rooms A and B. If 10 students are sent from  [#permalink]

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09 Apr 2019, 19:36
1
1
AkshdeepS wrote:
There are two examinations rooms A and B. If 10 students are sent from A to B, then the number of students in each room is the same. If 20 candidates are sent from B to A, then the number of students in A is double the number of students in B. The number of students in room A is

a. 20

b. 80

c. 100

d. 150

e. 200

If 10 students are sent from A to B, then the number of students in each room is the same MEANS A=B+20, (as A-10=B+10)
If 20 candidates are sent from B to A, then the number of students in A is double the number of students in B. MEANS 2(B-20)=A+20. Substitute A as B+20..
=> 2B-40=B+20+20...B=80, so A=B+20=80+20=100..

OR

We can work from choices..

a. 20.... so B=0...Not possible

b. 80...... so B=60.. When 20 are given from B : B=40 and A=100...NO

c. 100...... so B=80.. When 20 are given from B : B=60 and A=120... YES 120 =2*60

C
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Re: There are two examinations rooms A and B. If 10 students are sent from  [#permalink]

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11 Apr 2019, 09:57
1
AkshdeepS wrote:
There are two examinations rooms A and B. If 10 students are sent from A to B, then the number of students in each room is the same. If 20 candidates are sent from B to A, then the number of students in A is double the number of students in B. The number of students in room A is

a. 20

b. 80

c. 100

d. 150

e. 200

AkshdeepS why is this question being tagged as 700?

solution is <30 secs
let students A = x and class B = y
we need to find value of x
case 1 ; x-10=y-10
so y = x-20-- ( a)

case 2; x+20= 2*(y-20)
x+20 = 2y-40
substitute value of y from (a)
we get
x+20= 2*(x-20)-40
x+20=2x-40-40
or say x= 100
IMO C
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There are two examinations rooms A and B. If 10 students are sent from  [#permalink]

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11 Apr 2019, 10:12
Archit3110 wrote:
AkshdeepS wrote:
There are two examinations rooms A and B. If 10 students are sent from A to B, then the number of students in each room is the same. If 20 candidates are sent from B to A, then the number of students in A is double the number of students in B. The number of students in room A is

a. 20

b. 80

c. 100

d. 150

e. 200

AkshdeepS why is this question being tagged as 700?

solution is <30 secs
let students A = x and class B = y
we need to find value of x
case 1 ; x-10=y-10
so y = x-20-- ( a)

case 2; x+20= 2*(y-20)
x+20 = 2y-40
substitute value of y from (a)
we get
x+20= 2*(x-20)-40
x+20=2x-40-40
or say x= 100
IMO C

Archit3110 : Stats of the question are also saying a 700+ level .
Please think of people like me who are struggling in quant.
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Re: There are two examinations rooms A and B. If 10 students are sent from  [#permalink]

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11 Apr 2019, 10:22
AkshdeepS ; kind apologize but i did not mean to comment upon anyones skill or current preparation level, even I myself is sailing on the same boat called "GMAT" , well all I felt was that the question was of medium difficulty nevertheless until a question is relevant to gmat , it is then a good question to practise ..
keep posting such good questions..

AkshdeepS wrote:
Archit3110 wrote:
AkshdeepS wrote:
There are two examinations rooms A and B. If 10 students are sent from A to B, then the number of students in each room is the same. If 20 candidates are sent from B to A, then the number of students in A is double the number of students in B. The number of students in room A is

a. 20

b. 80

c. 100

d. 150

e. 200

AkshdeepS why is this question being tagged as 700?

solution is <30 secs
let students A = x and class B = y
we need to find value of x
case 1 ; x-10=y-10
so y = x-20-- ( a)

case 2; x+20= 2*(y-20)
x+20 = 2y-40
substitute value of y from (a)
we get
x+20= 2*(x-20)-40
x+20=2x-40-40
or say x= 100
IMO C

Stats of the question is also saying a 700+ level .
Please think of people like me who are struggling in quant.

_________________
If you liked my solution then please give Kudos. Kudos encourage active discussions.
SVP
Status: It's near - I can see.
Joined: 13 Apr 2013
Posts: 1596
Location: India
Concentration: International Business, Operations
Schools: INSEAD Jan '19
GPA: 3.01
WE: Engineering (Real Estate)
There are two examinations rooms A and B. If 10 students are sent from  [#permalink]

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11 Apr 2019, 10:32
Quote:
AkshdeepS ; kind apologize but i did not mean to comment upon anyones skill or current preparation level, even I myself is sailing on the same boat called "GMAT" , well all I felt was that the question was of medium difficulty nevertheless until a question is relevant to gmat , it is then a good question to practise ..
keep posting such good questions..

Archit3110 ; Not need to apologise bro as you said nothing sort of hurting. Neither you compared skills nor did you undermine anyone's. Good to have some lively chats and light moments, otherwise the GMAT journey is a pain that we expect to change in happiness sometime in future. We all are in the same boat till someone's profile shows a 700+ suddenly, and we think Ohh...one more left us behind..

Cheers: All the best.
_________________
"Do not watch clock; Do what it does. KEEP GOING."
CEO
Joined: 18 Aug 2017
Posts: 3006
Location: India
Concentration: Sustainability, Marketing
GPA: 4
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Re: There are two examinations rooms A and B. If 10 students are sent from  [#permalink]

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11 Apr 2019, 11:34
AkshdeepS wrote:
Quote:
AkshdeepS ; kind apologize but i did not mean to comment upon anyones skill or current preparation level, even I myself is sailing on the same boat called "GMAT" , well all I felt was that the question was of medium difficulty nevertheless until a question is relevant to gmat , it is then a good question to practise ..
keep posting such good questions..

Archit3110 ; Not need to apologise bro as you said nothing sort of hurting. Neither you compared skills nor did you undermine anyone's. Good to have some lively chats and light moments, otherwise the GMAT journey is a pain that we expect to change in happiness sometime in future. We all are in the same boat till someone's profile shows a 700+ suddenly, and we think Ohh...one more left us behind..

Cheers: All the best.

AkshdeepS .. thanks
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Re: There are two examinations rooms A and B. If 10 students are sent from  [#permalink]

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11 Apr 2019, 16:10
AkshdeepS wrote:
There are two examinations rooms A and B. If 10 students are sent from A to B, then the number of students in each room is the same. If 20 candidates are sent from B to A, then the number of students in A is double the number of students in B. The number of students in room A is

a. 20

b. 80

c. 100

d. 150

e. 200

Let the number of students in room a and b = x and y.

Eqn. 1:-$$x-10=y+10$$
or $$x-y=20$$

Eqn2:-$$x+20=2(y-20)$$
or $$2y-x=60$$

Solve for x and y

$$x=100, y=80,$$ IMO, Option C.
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Re: There are two examinations rooms A and B. If 10 students are sent from  [#permalink]

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11 Apr 2019, 23:46
Archit3110 wrote:
AkshdeepS wrote:
There are two examinations rooms A and B. If 10 students are sent from A to B, then the number of students in each room is the same. If 20 candidates are sent from B to A, then the number of students in A is double the number of students in B. The number of students in room A is

a. 20

b. 80

c. 100

d. 150

e. 200

AkshdeepS why is this question being tagged as 700?

solution is <30 secs
let students A = x and class B = y
we need to find value of x
case 1 ; x-10=y-10
so y = x-20-- ( a)

case 2; x+20= 2*(y-20)
x+20 = 2y-40
substitute value of y from (a)
we get
x+20= 2*(x-20)-40
x+20=2x-40-40
or say x= 100
IMO C

Not everyone can be in the same shoes buddy ! Would request pundits not to judge.
Intern
Joined: 15 Jan 2018
Posts: 21
There are two examinations rooms A and B. If 10 students are sent from  [#permalink]

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15 Apr 2019, 16:42
Another way to solve is to use the first condition as a qualifier for the second condition.

The first condition says, if 10 students are moved from A to B, then the class sizes are equal. This means that the difference in class sizes must be 20.

Now we must use the difference of 20 to qualify the answer choices for the second condition.
We will phrase this as can 2*(20 less than the number in B) = A+20?

In the following math, just remember that B is 20 less than A, which is how I get 0, 60, and 80.

A. Does 2(0-20) = (20+20)? No.

B. Does 2(60-20) = (80+20)? No.

C. Does 2(80-20) = (100+20)? Yes! Answer C
There are two examinations rooms A and B. If 10 students are sent from   [#permalink] 15 Apr 2019, 16:42
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# There are two examinations rooms A and B. If 10 students are sent from

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