A train travels from Delhi to Dehradun at the speed of 120 km/h and from Dehradun to Delhi at the speed of 130 km/h. What is the average speed during the whole journey?
Show answer & explanation
Correct answer: D
Explanation
The correct answer is option 4 i.e. 124.8 km/h
Formula used:
The average speed = Total distance covered/Total time taken
OR
The average speed = 2xy/(x + y)
where, x = the speed from A to B
y = The speed from B to A
Given that:
x = 120 km/h
y = 130km/h
Calculations:
The average speed = 2 * 120 * 130/(120 +130)
⇒ 13200/250 = 124.8 km/h