Aptitude - Time and Distance - Discussion
Discussion Forum : Time and Distance - General Questions (Q.No. 12)
12.
Robert is travelling on his cycle and has calculated to reach point A at 2 P.M. if he travels at 10 kmph, he will reach there at 12 noon if he travels at 15 kmph. At what speed must he travel to reach A at 1 P.M.?
Answer: Option
Explanation:
Let the distance travelled by x km.
| Then, | x | - | x | = 2 |
| 10 | 15 |
3x - 2x = 60
x = 60 km.
| Time taken to travel 60 km at 10 km/hr = |  |
60 |  hrs |
= 6 hrs. |
| 10 |
So, Robert started 6 hours before 2 P.M. i.e., at 8 A.M.
 Required speed = |
|
60 | kmph. |
= 12 kmph. |
| 5 |
Discussion:
93 comments Page 6 of 10.
Bharat said:
1 decade ago
x/10-x/15=2. How did 60 comes?
Tarun said:
1 decade ago
Let the traveled distance X.
Then X/10-X/15 = 2.
X = 60 kmph.
Time taken to travel 60 km at 10 kmph is 6 hours.
So the Mr stylish Yankee Robert Peterson a billionaire person started 6 hours before 2 pm. i.e 8 pm.
Speed of Mr equals to 60/(8 pm-1 pm) = 12 kmph.
Then X/10-X/15 = 2.
X = 60 kmph.
Time taken to travel 60 km at 10 kmph is 6 hours.
So the Mr stylish Yankee Robert Peterson a billionaire person started 6 hours before 2 pm. i.e 8 pm.
Speed of Mr equals to 60/(8 pm-1 pm) = 12 kmph.
Param said:
1 decade ago
Distance is same in both the cases:
So :: let's the time taken to reach at 2 pm be t.
And then time taken to reach at 12 pm will be t-2(2-12 = 2 hours).
As distance is same:
t*10 = t-2*15.
Giving t = 6 hours (to reach at 2, time taken is 6 hours).
Total distance = 6*10 = 60 KM.
Now to reach at 1 PM speed = d/t.
s = 60/t-1 = 60/6-1 = 12.
Why 6-1? Because (2 pm - 1 pm = 1 hour and we calculated t as 6).
Hope this helps.
So :: let's the time taken to reach at 2 pm be t.
And then time taken to reach at 12 pm will be t-2(2-12 = 2 hours).
As distance is same:
t*10 = t-2*15.
Giving t = 6 hours (to reach at 2, time taken is 6 hours).
Total distance = 6*10 = 60 KM.
Now to reach at 1 PM speed = d/t.
s = 60/t-1 = 60/6-1 = 12.
Why 6-1? Because (2 pm - 1 pm = 1 hour and we calculated t as 6).
Hope this helps.
Harish said:
1 decade ago
At 15 kmph ---> 2 p.m.
_?_kmph ---> 1 p.m.
10 kmph ---> 12 a.m.
So in between 12 am and 2 pm, 1 pm lies in between.
(10+15)/2 = 12.5 which is nearer to 12.
_?_kmph ---> 1 p.m.
10 kmph ---> 12 a.m.
So in between 12 am and 2 pm, 1 pm lies in between.
(10+15)/2 = 12.5 which is nearer to 12.
Geeta said:
1 decade ago
Simple.
10 = d/t.
d = 10t.
15 = d/t-2.
15 = 10t/t-2.
15t-30 = 10t.
15t-10t = 30.
5t = 30.
t = 6.
S = d/t-1.
S = 10t/t-1 substitute from above.
S = 10*6/6-1.
S = 60/5.
S = 12 km/h.
10 = d/t.
d = 10t.
15 = d/t-2.
15 = 10t/t-2.
15t-30 = 10t.
15t-10t = 30.
5t = 30.
t = 6.
S = d/t-1.
S = 10t/t-1 substitute from above.
S = 10*6/6-1.
S = 60/5.
S = 12 km/h.
Ammad Arshad said:
1 decade ago
10km/h = d/x; -- (1);
15km /h = d/(x-2);--- (2);
By comparing both equation 1 and 2 we get total time.
15(x-2) = 10x;
15x -30 = 10x;
5x = 30;
x = 6h;
Put the value of x in equation 1 we got distance.
d = 60km.
As from the state we know that.
y = d/(x-1); -- (3);
Put the value of d and x in equation 3.
y = 60/(6-1).
y = 60/5.
y = 12 kmph Answer.
15km /h = d/(x-2);--- (2);
By comparing both equation 1 and 2 we get total time.
15(x-2) = 10x;
15x -30 = 10x;
5x = 30;
x = 6h;
Put the value of x in equation 1 we got distance.
d = 60km.
As from the state we know that.
y = d/(x-1); -- (3);
Put the value of d and x in equation 3.
y = 60/(6-1).
y = 60/5.
y = 12 kmph Answer.
Nancy said:
1 decade ago
Yes, but why we are considering only 10 km/hr speed?
Why not 15 km/hr?
Why not 15 km/hr?
Karthika said:
1 decade ago
Same distance but with different speeds.
The difference in time is 2 hours.
Let the distance be x.
X/10-x/15 = 2.
=> x = 60 kms.
Calculate time in first case i.e. 60/10 = 6 hours.
=> he took 6 hours to reach the destination.
The question is at 1 p.m => speed to reach destination in 5 hours.
We know that speed is inversely proportional to time.
s1/s2 = t2/t1.
10/x = 5/6.
=> x = 12 kmph.
The difference in time is 2 hours.
Let the distance be x.
X/10-x/15 = 2.
=> x = 60 kms.
Calculate time in first case i.e. 60/10 = 6 hours.
=> he took 6 hours to reach the destination.
The question is at 1 p.m => speed to reach destination in 5 hours.
We know that speed is inversely proportional to time.
s1/s2 = t2/t1.
10/x = 5/6.
=> x = 12 kmph.
Mohit said:
1 decade ago
Let time at 12noon be x hours.
Time at 2pm will be x+2.
Speed = distance*time.
So, 15*x = 10*(x+2).
x = 20/5 = 4km.
Distance = 15*4 = 60km.
Speed at 1pm = 60/5 = 12kmph.
Time at 2pm will be x+2.
Speed = distance*time.
So, 15*x = 10*(x+2).
x = 20/5 = 4km.
Distance = 15*4 = 60km.
Speed at 1pm = 60/5 = 12kmph.
Shashank said:
1 decade ago
We can use net speed formula = 2xy/x+y.
Because the distance travelled is same,
So => 2*10*15/(10+15) = 12.
Because the distance travelled is same,
So => 2*10*15/(10+15) = 12.
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