Rohan had to travel from A to B. He covers 75% of the distance at a speed of 60 km/h and the remaining distance at a speed of 40 km/h. What was his average speed for the entire journey?

Correct option is B

Given:

75% of the distance is covered at 60 km/h

25% of the distance is covered at 40 km/h

Formula Used:

​$$\text{Average Speed} = \frac{\text{Total Distance}}{\text{Total Time Taken}}$$​​

Solution:

Assume total distance = 100 km

Distance₁ = 75 km, Speed₁ = 60 km/h

Distance₂ = 25 km, Speed₂ = 40 km/h

Time₁ = $$\frac{75 }{ 60}$$​ = 1.25 h

Time₂ = $$\frac{25 }{ 40 }$$​= 0.625 h
Total time = 1.25 + 0.625 = 1.875 h
Total distance = 100 km

Average Speed $$= \frac{100}{1.875} =$$​53$$\frac 13$$​ km/h