1.
Train A crosses a pole in 20 seconds and Train B crosses the same pole in one minute. The length of Train A is half of the length of Train B. what is the ratio of the speed of Train A to that of Train B?
Answer: Option 'A'
Let the length of Train B be 2x and that of Train A be X.
Speed of Train A = x/20
Speed of Train B = 2x/60 = x/30
Ratio = Speed A/Speed B = X × 30/X * 20 = 3/2
2.
The average speed of a train is 1(3⁄7) the average speed of a car. The car covers a distance of 588 km in 6 hours. How much distance will the train cover in 13 hours?
Answer: Option 'D'
Speed of the car = 588/6 = 98 km/hr
Speed of train = (10/7) x 98 = 140 km/hr
Distance covered by the train in 13 hours = 140 x 13 = 1820 km
3.
A train 800 m long is running at a speed of 78 km/hr. If it crosses a tunnel in 1 minute, then the length of the tunnel is:
Answer: Option 'B'
Given, Length of the train = 800 m
Speed of the train = 78 km/hr (convert km/hr to m/sec)
= 78 × (5/18) m /sec
= 21.667 m /sec
=> Speed of the train = 21.667 m /sec
Time taken by the train to cross the tunnel = 1 min = 60 sec
To find the length of the tunnel:
Time taken by train to cross tunnel = (Length of tunnel + Length of train) / speed of the train
=> 60 = (Length of tunnel + 800) / 21.667
=> 60 × 21.667 = Length of tunnel + 800
=> 1300 = Length of tunnel + 800
=> 1300 – 800 = Length of tunnel
=> 500 = Length of tunnel
Thus, the Length of tunnel = 500 m
4.
A train passes a station platform in 36 seconds and a man standing on the platform in 20 seconds. If the speed of the train is 54 km/hr ,what is the length of the platform?
Answer: Option 'B'
Given, time taken by train to pass the man = 20 sec
Speed of the train = 54 km/hr
---> Converting into meter/sec
=> Speed of train =54 × (5/18) m/sec = 15 m/sec
W.K.T: Speed of train = Length of train/ Time taken by train to pass the man
=> 15 =Length of train / 20
=>Length of train = 15 × 20
=>Length of train = 300 metre.
Given,A train passes a station platform in 36 seconds.
=>Speed of train = (Length of train + Length of platform) / Time taken by train to pass the platform
=> 15 = (300 +Length of platform) / 36
=> 15 × 36 = (300+Length of platform)
=> 540 =300+Length of platform
=> 540 - 300 =Length of platform
Thus,Length of platform = 240 meter.
5.
A person drove a certain distance by car at the speed of 35 km/h and returned on cycle at the speed of 10 km/h, if the whole journey took 18 hours. Then what total distance covered by the person?
Answer: Option 'C'
Let the distance be x km
Time taken by car = x/35 and time taken on cycle = x/10
x/10 + x/35 = 18
x = 140 km