Question

i shall be 20 minutes late if I walk at 3 km/hr and 10 minutes ago if I walk at 4 km/hr. How far I have to walk?​

Answer 1

Given:

Speed when you will be 20 minutes late = 3km/hr

Speed when you reach 10 minutes early = 4 km/hr

To find:

How far you have to walk.

Solution:

Let the distance to be travelled be x km.

In the first case if we wish to reach on time then we must take 20 minutes less therefore the time needed to just reach on time with a speed of 3 km/hr should be = x/3 - 20/60

While in the second case we reach 10 minutes earlier therefore time needed to just reach on time with a speed of 4 km/hr should include the extra time= x/4+ 10/60

The two times should be equal:

x/3 - 1/3 = x/4 + 1/6

x/3 - x/4 = 1/6 + 1/3

x/12 = 1/2

x = 6 km

Therefore the distance to be travelled is 6 km.