Rohan divides his complete journey in three equal parts and covers the first part at a speed of 30 km/h, the second part at 40 km/h and the last part at 50 km/h with his car. What is the average speed (in km/h) of his car during his entire journey?
Show answer & explanation
Correct answer: A
Explanation
The correct answer is option 1 i.e. 38.
Rohan divides his journey into three equal parts.
Speed during the first part = 30 km/h
Speed during the second part = 40 km/h
Speed during the third part = 50 km/h
Average speed = 3/(1/30 + 1/40 + 1/50) = 3(300)/(10 + 7.5 + 6) = 900/23.5 = 38 km/h