A car travels four consecutive distances of 2 km each at speeds of 10 km/hr, 20 km/hr, 30 km/hr, and 40 km/hr, respectively. What is the average speed of the car (in km/hr) over this total distance?
Show answer & explanation
Correct answer: C
Explanation
The correct answer is option 3 i.e. 19.2.
Total distance = 4 × 2 = 8 km
Time taken for each segment:
2 km at 10 km/hr = 2/10 = 0.2 hr
2 km at 20 km/hr = 2/20 = 0.1 hr
2 km at 30 km/hr = 2/30 ≈ 0.0667 hr
2 km at 40 km/hr = 2/40 = 0.05 hr
Total time = 0.2 + 0.1 + 0.0667 + 0.05 = 0.4167 hr
Average speed = Total distance / Total time = 8 / 0.4167 ≈ 19.2 km/hr