During a journey of 120 km, Rahi drives first 60 km at the speed of 60 km/h, next 30 km at 60 km/h and the remaining 30 km at the speed of 30 km/h. Determine the average speed.
Answer & explanation
Correct answer: option 1
Distance = Speed × Time
Time 1 = \(\frac{Distance }{Speed}\)
= \(\frac{60 }{60}\) = 1 hour
Time 2 = \(\frac{30 }{60}\) = 0.5 hour
Time 3 = \(\frac{30 }{30}\) = 1 hour
Average speed = \(\frac{120 }{1 + 0.5 + 1}\)
= \(\frac{120 }{2.5}\)
= 48 km/h