Question

A car travels 100 km at a speed of 60km/hr and return with speed of40km/hr calculate the average speed of the whole journey

Answer 1

Distance = 100km

Speed = 60km/hr

Time taken = Distance/ Speed = 100/60 = 5/3hr = 100minutes

Speed of car while returning = 40km/hr

Time taken = 100/40 = 2.5hr = 150minutes

Average speed of car of the whole journey= Total Distance/ Total time

Total Distance = 100+100 = 200km

Total time = 5/3 + 5/2 = 25/6 hr

Average speed = $\frac{200}{ \frac{25}{6} }$

=> 8×6

=>48km/hr.

Cheers!