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:
20
80
100
200
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:
74 comments Page 1 of 8.

Doss said:   1 decade ago
Dear friend explain with example.........

PRAKASH said:   1 decade ago
I don't know how 2 was came at step 2.

Please explain.

Rcahana said:   1 decade ago
Please help me solve this.

Akilapriya said:   1 decade ago
I can't understand the sentence "then the number of students in A is double the number of students in B" explain me.

Mmmm said:   1 decade ago
Tell me clearly. Please.

Sundar said:   1 decade ago
Assume x,y

x-a, y-b

10 students from b-a. So x-b,then y+b

Now doubled

2(y-20) then both equation solved.

Prasu said:   1 decade ago
Based on the answer a=100 and b=80. They said that if 20 sent from a to b then.

A will become double of b.

So if 20 sent then a=120 and b=60 i.e. a is double of b.

Basheerbi said:   1 decade ago
I can't understand the prasu explanation tell me clearly.

Sandy said:   1 decade ago
Can you explain by assuming a = 100?

Raji said:   1 decade ago
Take these two cases individually let us look first through options 1st option is 20 so to apply both conditions is not possible so come to 80 so given if 10 people are sent to b then people in both class rooms are same so definetly b will be 60.

So again now apply second condition individually so by sending 20 people 4rm b A is twice that of B so this condition is not satisfied so now take 100 and check then both conditions satisfy and hence ans is 100


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