Aptitude - Time and Distance - Discussion

Actual distance traveled be X km.

X/10 = X+20/14.

X = 50 kmph.

I can't understand please explain clearly.

It came by this formula S = D/T (Speed = Distance/Time).

Here we take this formula such as:

T = D/S.

Let consider actual distance x km.

T = x/10.....(1).
T = x+20/14.....(2).

Taking both the times together we get from (1) and (2).

x/10 = x+20/14.
14x = 10x+200.

4x = 200.
x = 50km.

Hope you get it now.

Here time is never given.

So consider man named.

Ashok walk with speed 10 km/hr, he travel for next 2 hour so distance he cover is 20 km.

2nd person named.

Madhu walk with speed 14 km/hr, he also travel for 2 hour so distance he cover is 28 km.

Now Madhu travel more 20 km wit speed 14 km/hr. So we subtract that 20 km from distance he travel in 2 hour.

= 28-20 = 8 km.

It means if we consider time 2 hour. Which is not given, so the answer will be 8 km?

Is it true?

Difference of speed 14-10 = 4.

Therefore 4 km ----> 20.

So 10 km to travels 50 km.

14x-10x = 20.
4x = 20.
x = 5.

Actual distance = 10*5 = 50.

5*10 = 50 because t = 5 and Distance = Speed*Time.

It is very clear. The time in both the cases is same that is 5 hrs.

T = 5;

Now the distance travelled by him at a speed of 10 kmph is x/10 in 5 hrs.

Similarly the distance travelled by him at a speed of 14 kmph is (x+20)/14 in 5 hrs.

Form that we can say that x/10 = 5, and (x+20)/14 = 5;
From the above x/10 = (x+20)/14.

Solve this you will get the answer.

Speed 40% of x = 20.

Solving x =50.

10km/hr-------------->x km.
14km/hr-------------->x+20 km.

So cross multiplication,
10(x+20) = 14x.
10x+200 =14x.
200 = 14x-10x.
200 = 4x.
x = 50 km.