A train travel some distance with a speed of 30km/hr and return with a speed of 45km/hr. Calculate average speed.
See previous post.
To calculate the average speed, we need to find the total distance traveled and the total time taken.
Let's assume the distance traveled in one direction is D km.
To find the total distance, we need to consider both the forward and return journeys.
Distance traveled in one direction = D km
Distance traveled in the return journey = D km
Total distance = D + D = 2D km
Now, we need to find the total time taken for the round trip.
Time taken in one direction = Distance / Speed = D km / 30 km/hr = D/30 hr
Time taken in the return journey = Distance / Speed = D km / 45 km/hr = D/45 hr
Total time taken = Time taken in one direction + Time taken in the return journey
= D/30 + D/45 hr
= (3D + 2D) / 90 hr
= 5D / 90 hr
Finally, to find the average speed, we divide the total distance by the total time taken.
Average speed = Total distance / Total time taken
= (2D km) / (5D/90 hr)
= 2D * (90/5D) km/hr
= 36 km/hr
Therefore, the average speed of the train is 36 km/hr.