A car travels three equal distances at the speed of 10 km/hr, 30 km/hr and 60 km/hr respectively. What is the average speed (in km/hr) for this journey?
Show answer & explanation
Correct answer: C
Explanation
Average speed = 3xyz / (xy + yz + zx)
x = 10, y = 30, z = 60
= (3 × 10 × 30 × 60) / (300 + 1800 + 600)
= 54000 / 2700
= 20 km/h