A man goes to a place in the car at speed of 160 km/h and comes back at a lower speed. If the average speed is 64 km/h in total, then the return speed (in km/h) is:
Answer & explanation
Correct answer: option 3
We know ,
Average speed = \(\frac{2 × S1 ×S2 }{S1 + S2}\)
According to question ,
64 = \(\frac{2 × 160 × S2 }{160 + S2}\)
160 + S2 = \(\frac{2 × 160 × S2 }{64}\)
4 × S2 = 160 km
S2 = 40 km/h
So , Speed while returning back is 40 km/h