Aptitude - Time and Distance - Discussion

Let distance travelled by person at 14km/h be d1 and distance travelled at 10km/h be d2.

d1-d2=20km (given in Q that he walks 20km more)
D=speed * time.

{Time is constant and reason is;

It is because supposed for example if a person walks 10km/h for 7 hrs means he would have covered 70km. If speed changes to 14km/h and if we assume time is not constant then to cover 70km distance at 14km/h 5hrs would be needed, then in such case there would be no case of extra distance covered like in present Q which is 20km.

If time is constant like 7hrs so at distance at 10km/h =70km & 14km/h=98km and only then we can say it travelled 28km extra)}

Now coming to the present Q,
d1-d2=20km,
14t-10t=20.
t(14-10)=20.
4t=20.
T=5hr.

Q says if a person walks 14km/h that means 14km/h is not the original speed...
D=10*5=50km.

Thank you for explaining @Kinnari.

@Ilesh @Jayesh.

You guys made it simpler to understand. Thank you very much.

Thanks @Kinnari.

S=14km/hr d=20km

T=d/s, So, 14/20= 5hrs,

Now we have T=5hrs and s=10km/hr is the actual speed he needs to go.

S=10 T=5

Now, d= S x T.
=10*-5.
= 50 km.
That's all.

He travel 14kmph instead of 10kmph,
So,
14 - 10=4.

Walked 20km more(distance÷speed)=time.

20÷4=5.

Actual distance is 10 * 5=50km. (Distance=time*speed).

Instead of 10 kmph he is walking 14kmph which means he is walking 4 kmph more and totally he walks 20 km.

Hence, 20/4=5.

If we take this for 10 kmph then x it by 5 which means 5* 50= 50kmph.

Can anyone tell me whether we can solve it like this?

Most people have the confusion that time is equal has not been stated equal in the question, Then, how can we equate the two entities based on the assuption that time is equal, right?


Let me explain;
if t=1st hour, distance=10...also, distance=14
t=2nd hour, distance=20...also distance=14+14=28
..
.
Similarly when t=5th hour, distance=50...distance=70
Now, the difference in respective distances =70-50=20
This means that the distance covered is 20 more in the 5th hour when speed is 14kmph instead of 10kmph.
This means, in the same time, the distance covered is different(i.e. 20km more->as stated in the question)
This proves that the time interval is the same irrespective of speed is different.
So, we equated the two statements since the time taken has to be the same. Hope you got it.

He travels 4 km/hr extra in the other case.

So if he traveled 20 km more in that case then it means the time he took would be time= distance/speed = 20/4= 5 hours. So now that we know the time he took, we can find the actual distance he traveled.

Distance= speed* time= 10*5= 50 km.

14km/hr - 10 km/hr = 4 km/hr(difference)
4km/hr - 20km,
10km/hr (?),
= 10*20/4.
= 50km.