A car travelled distances of 10 km, 20 km and 30 km at speeds of 30 km/h, 40 km/h and 60 km/h, respectively. The average speed of the car is:
Answer & explanation
Correct answer: option 1
Average Speed = \(\frac{Total\; Distance }{Total\; Time }\)
Distance = Speed × Time
Total distance = 10 + 20 + 30= 60 km
Total time = \(\frac{10 }{30 }\) + \(\frac{20 }{40 }\) + \(\frac{30 }{60}\) = \(\frac{1 }{3 }\) + 1
= \(\frac{4 }{3 }\)
Average speed = \(\frac{60 × 3 }{4 }\) = 45 km/h