Aptitude - Time and Distance - Discussion
Discussion Forum : Time and Distance - General Questions (Q.No. 15)
15.
A man covered a certain distance at some speed. Had he moved 3 kmph faster, he would have taken 40 minutes less. If he had moved 2 kmph slower, he would have taken 40 minutes more. The distance (in km) is:
Answer: Option
Explanation:
Let distance = x km and usual rate = y kmph.
| Then, | x | - | x | = | 40 |  2y(y + 3) = 9x ....(i) |
| y | y + 3 | 60 |
| And, | x | - | x | = | 40 | y(y - 2) = 3x ....(ii) |
| y -2 | y | 60 |
On dividing (i) by (ii), we get: x = 40.
Discussion:
118 comments Page 11 of 12.
Eswar said:
1 decade ago
@Shathi.
Why sivaram method is not correct way?
Speed*time=distance.
Differnce of speed and time= distance.
3*40-2*40=x.
120-80=x.
40=x.
Why sivaram method is not correct way?
Speed*time=distance.
Differnce of speed and time= distance.
3*40-2*40=x.
120-80=x.
40=x.
Aniruddha said:
1 decade ago
In problem when it says 40 min less then we substract.
But when it says 40 min more then how come we still substract?
Please tell basic concept while deciding wheter to add or substract.
But when it says 40 min more then how come we still substract?
Please tell basic concept while deciding wheter to add or substract.
Ash said:
1 decade ago
Devide both the equations
2y(y+3) 9x
------- =
y(y-2) 3x
2y(y+3) 9x
------- =
y(y-2) 3x
Shro said:
1 decade ago
I am not understanding as not able to calculate this lines from the given explanation:
2y(y + 3) = 9x ....(i)
y(y - 2) = 3x ....(ii)
Somebody tell me step by step calculation of how to get above answer.
And also @ Amit :
not understanding this line
How you got Y=12?
and as per your equation:
why didn u consider x/y in the whole sum?
As in the question it is given a certain distance at some speed.
So we should take x/y also.
Your method looks bit simple but I got all this doubts so am asking here .
Please kindly someone explain me explicitly.
thank you :)
2y(y + 3) = 9x ....(i)
y(y - 2) = 3x ....(ii)
Somebody tell me step by step calculation of how to get above answer.
And also @ Amit :
not understanding this line
How you got Y=12?
and as per your equation:
why didn u consider x/y in the whole sum?
As in the question it is given a certain distance at some speed.
So we should take x/y also.
Your method looks bit simple but I got all this doubts so am asking here .
Please kindly someone explain me explicitly.
thank you :)
Deepika said:
1 decade ago
3 kmph (faster) - 2 kmph(slower) = 1kmph
1 kmph * 40 minutes = 40.
1 kmph * 40 minutes = 40.
Prasanna said:
1 decade ago
Can any of you please explain how 2 solve that equations in detail please.
Shakti said:
1 decade ago
Sivaram:I don't think its a correct way to solve this quesion.
Dilip said:
1 decade ago
How did you get y as 12 ? I am unable to solve the equation.
Bhavana said:
1 decade ago
Good explanation by Amit kr Soni, Sivaraman and Amit.
Sivaram said:
1 decade ago
There is simple method
3*40=120
2*40=80
Then subtract two we get 40 this simple
3*40=120
2*40=80
Then subtract two we get 40 this simple
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