A train travels the first 30 km of 120 km track with a uniform speed of 30 km / h. What should be the speed of the train to cover the remaining distance of the track so that its average speed is 60 km/h for the entire trip?
Answers
Answer:
90 Km/h
Explanation:
A train has to travel for 120 km
Out of that, it travels 30 km with uniform speed of 30 km/h.
Therefore, time taken = distance/speed
=> t1 = 30/30
=> t1 = 1 h
To find the speed for remaining distance.
Let, the speed be 'v'
Now, remaining distance = 120 - 30 = 90 km
Therefore, time taken = distance/speed
=> t2 = 90/v
Now, for the entire journey, we have,
=> 60 km/h = total distance/total time
=> 60 = 120/(t1+t2)
=> t1 + t2 = 120/60
=> t1 + t2 = 2
=> 1 + 90/v = 2
=> 90/v = 2-1
=> 90/v = 1
=> v = 90
Hence, required speed of the train is 90 km/h.
Answer:
The remaining distance must be covered in 90 km/h.
Explanation:
Train travels the 1st 30 km with a speed of 30 km/h.
Let the speed for the remaining 90 km be x km/h.
Average speed= (speed 1+speed 2)/2=60 km/h
or, (30 km/h+x km/h)/2 =60 km/h
or, 30 km/h+x km/h=120 km/h
or, x km/h=(120-30)=90 km/h
HOPE THAT THIS HELPS YOU!
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