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 4 of 12.
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.
Puneet negi said:
8 years ago
S(s+3)*40/60 = s(s-2)*40/60
----------------------. ------------------
3. 2
S=12 putting in any of side l.h.s or r.h. s we get required answer 40.
----------------------. ------------------
3. 2
S=12 putting in any of side l.h.s or r.h. s we get required answer 40.
Jeevitha said:
1 decade ago
2y(y+3) = 9x.
(y cancel each other and 9x/3x=3).
y(y-2) = 3x.
After that we get:
2(y+3) = 3(y-2).
2y+6 = 3(y-2).
2y+6 = 3y-6.
6+6 = 3y-2y.
12 = y.
Therefore y = 12.
(y cancel each other and 9x/3x=3).
y(y-2) = 3x.
After that we get:
2(y+3) = 3(y-2).
2y+6 = 3(y-2).
2y+6 = 3y-6.
6+6 = 3y-2y.
12 = y.
Therefore y = 12.
Manish said:
9 years ago
WE KNOW,
DISTANCE = SPEED * TIME.
Then,
(speed+3) * (time - 40/60) = (speed - 2) (time + 40/60) = distance, I am not getting answer,
Can anyone explain by this method?
DISTANCE = SPEED * TIME.
Then,
(speed+3) * (time - 40/60) = (speed - 2) (time + 40/60) = distance, I am not getting answer,
Can anyone explain by this method?
Jay said:
1 decade ago
@Snega,
Why you take t = d/x.
Just consider 2 and 4 equation.
Solve the equation. But we can't get the answer. What is the problem in that?
Just explain me please.
Why you take t = d/x.
Just consider 2 and 4 equation.
Solve the equation. But we can't get the answer. What is the problem in that?
Just explain me please.
Jagdish said:
3 years ago
Divide both the equations.
2y(y+3) 9x.
------- =
y(y-2) 3x.
Solution:
2(y+3)÷y(y-2) = 9x÷ 3x.
2(y+3)÷(y-2) = 3,
2(y+3) = 3(y-2),
2y+6= 3y-6.
3y-2y = 6+6.
Y =12.
2y(y+3) 9x.
------- =
y(y-2) 3x.
Solution:
2(y+3)÷y(y-2) = 9x÷ 3x.
2(y+3)÷(y-2) = 3,
2(y+3) = 3(y-2),
2y+6= 3y-6.
3y-2y = 6+6.
Y =12.
(8)
Amit said:
8 years ago
Hi,
3*40 =120
2*40 = 80
120-80 = 40.
In this one quantity is in hr and second one is in minutes how you cancel the different units.
km/hr*min not relevant.
3*40 =120
2*40 = 80
120-80 = 40.
In this one quantity is in hr and second one is in minutes how you cancel the different units.
km/hr*min not relevant.
Arpan said:
1 decade ago
I don't know when to subtract and when to add.
Please give me idea on this.
Here in equation it is taken minus.
And in previous example it was taken add.
Please give me idea on this.
Here in equation it is taken minus.
And in previous example it was taken add.
Shiva said:
8 years ago
Why they took 60 there, please can anyone give a brief explanation regarding those equations x/y - (x/(y+3)) = 40/60? And the second equation as well.
Ruku said:
7 years ago
The distance is simply.
As if he is speed 3kmph then it takes 40 less,
And if his speed 2kmph then it takes 40 more,
(3 * 40)-(2 * 40)=120-80.
= 40km.
As if he is speed 3kmph then it takes 40 less,
And if his speed 2kmph then it takes 40 more,
(3 * 40)-(2 * 40)=120-80.
= 40km.
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