Speed, Time and Distance
 Two trains A and B travel from points X to Y and the ratio of the speeds of A to that of B is 2 : 7. Find the ratio of time taken by A and B to reach From X to Y.

 2 : 5
 3 : 5
 3 : 8
 7 : 2

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We know that speed is inversely proportional to time.
Given that, (Speed of A ) : (speed of B ) = 2 : 7Correct Option: D
We know that speed is inversely proportional to time.
Given that, (Speed of A ) : (speed of B ) = 2 : 7
∴(Time taken by A ) : (Time taken by B ) = 1/2 : 1/7 = 7 : 2
 A man completes 30 km of a journey at 6 km/h and the remaining 40 km of the journey in 5 h. Find the average speed for the whole journey.

 6^{4}/_{11} km/h
 7 km/h
 7^{1}/_{2}
 8 km/h

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Total distance = 30 + 40 = 70 km
Total time taken = (30/6) + 5 = 10 hCorrect Option: B
Total distance = 30 + 40 = 70 km
Total time taken = (30/6) + 5 = 10 h
∴ Required average speed = 70/10 = 7 km/h
 A certain distance is covered at a certain speed. If half of the distance is covered in double time, the ratio of the two speeds is .

 4 : 1
 1 : 4
 1 : 2
 2 : 1

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Let L km distance be covered in T h. So, speed in first case = L/T km/h.
And speed in second case = (L/2)/2T = L/4T km/hCorrect Option: A
Let L km distance be covered in T h. So, speed in first case = L/T km/h.
And speed in second case = (L/2)/2T = L/4T km/h
∴ Required ratio = L/T : L/4T =1 : 1/4 = 4 : 1
 Moving 6/7 of its usual speed a train is 10 min late. Find its usual time to cover the journey.

 25 min
 15 min
 35 min
 60 min

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New speed = 6/7 of usual speed
Now, time taken = 7/6 of usual time
(7/6 of the usual time)  (usual time) = 10 minCorrect Option: D
New speed = 6/7 of usual speed
Now, time taken = 7/6 of usual time
(7/6 of the usual time)  (usual time) = 10 min
⇒ 1/6 of the usual time = 10 min
∴ Usual time = 60 min
 John started from A to B and Vinod from B to A. If the distance betweeen A and B is 125 km and they meet at 75 km from A, what is the ratio of John's speed to that of Vinod's speed?

 2 : 3
 3 : 2
 4 : 3
 5 : 4

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John's speed : Vinod's speed = 75 : ( 125  75 )
Correct Option: B
John's speed : Vinod's speed = 75 : ( 125  75 )
= 75 : 50 = 3 : 2