The average speed of Gaurav during a two-ways journey is 15 km/h. If he walked a distance of 20 km every hour while going, then his speed while returning will be :

Correct option is C

Given:

Average Speed of Gaurav during a two-ways journey = 15km/hr

Speed while going = 20km/hr

Formula Used:

​$$Time = \frac{Distance}{Speed}$$​​

Solution:

Let the distance on one side be x

Then time taken while going =$$\frac{x}{20}$$​​

Total time taken of the journey =$$\frac{2x}{15}$$​​

Let the speed while returning be v

Then:

$$\frac{2x}{15} = \frac{x}{20} + \frac{x}{v}$$​

​$$\frac{x}{v} = \frac{8x - 3x}{60}$$​​

​$$\frac{x}{v} = \frac{5x}{60}$$​​

​$$v= \frac{60 \times x}{5x} = 12km/hr$$​​