Aptitude - Simplification - Discussion
Discussion Forum : Simplification - General Questions (Q.No. 2)
2.
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:
Answer: Option
Explanation:
Let the number of students in rooms A and B be x and y respectively.
Then, x - 10 = y + 10 
x - y = 20 .... (i)
and x + 20 = 2(y - 20) x - 2y = -60 .... (ii)
Solving (i) and (ii) we get: x = 100 , y = 80.
The required answer A = 100.
Discussion:
78 comments Page 7 of 8.
Naveena said:
1 decade ago
Friends you are doing upto x and why values. But we have to double the A also comparing to B.
Doss said:
2 decades ago
Dear friend explain with example.........
Koteswararao chimmili said:
10 years ago
If 10 students are sent from A to B,then the number of students in each room is the same
a-10 = b+10 ; ---- (1)
If 20 candidates are sent from B to A, then the number of students in A is double the number of students in B.
a+20 = 2(b -20); ---- (2) ( suppose A=10,B=5 that means A=2B then 10=10 )
Equation 1
a-10 = b+10.
a-b = 20.
Equation 2
a+20 = 2(b-20)
a+20 = 2b -40
a-2b = -60.
Solving equation 1 and 2
a-b = 20
a-2b = -60 (-a+2b = +60)
_____________.
b = 80
b is substitute in equation 1
a - b = 20
a = 20 + b
a = 20 + 80
a = 100
The answer is a = 100
a-10 = b+10 ; ---- (1)
If 20 candidates are sent from B to A, then the number of students in A is double the number of students in B.
a+20 = 2(b -20); ---- (2) ( suppose A=10,B=5 that means A=2B then 10=10 )
Equation 1
a-10 = b+10.
a-b = 20.
Equation 2
a+20 = 2(b-20)
a+20 = 2b -40
a-2b = -60.
Solving equation 1 and 2
a-b = 20
a-2b = -60 (-a+2b = +60)
_____________.
b = 80
b is substitute in equation 1
a - b = 20
a = 20 + b
a = 20 + 80
a = 100
The answer is a = 100
Suman said:
10 years ago
Well explained @Tamil.
Srividya said:
10 years ago
Friends as the question had given that A is doubled then why we doubled B? Can anyone explain this problem in another process?
Rajesh said:
10 years ago
We can find out the answer by option if the 1st option is 80. Consider the student of class B and transfer 10 students then in both the class are equal so definitely, A class has a 100 student then tally it.
Ramesh.Mariyada said:
10 years ago
Exactly I have the same doubt as same as @Nandhakumar.
Can anyone help us?
Can anyone help us?
Cgyel said:
1 decade ago
If A is double then, Why 2 (y - 20)?
Kavya said:
1 decade ago
It is A which is double. So the equation should be 2 (x + 20) = y - 20. Right?
Akshay said:
9 years ago
Nice explanation, Thanks @Manojkumar.
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