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Two stations A and B are 110 km apart on a straight line. One train starts from A at 7 a.m. and travels towards B at 20 kmph. Another train starts from B at 8 a.m. and travels towards A at a speed of 25 kmph. At what time will they meet?
Answer: Option (B) 10 a.m. Explanation: Suppose they meet x hours after 7 a.m. Distance covered by A in x hours = 20x km. Distance covered by B in (x - 1) hours = 25(x - 1) km. Therefore 20x + 25(x - 1) = 110 => 45x = 135 => x = 3. So, they meet at 10 a.m.
Answer: Option (B) 10 a.m.
Explanation:
Suppose they meet x hours after 7 a.m.
Distance covered by A in x hours = 20x km.
Distance covered by B in (x – 1) hours = 25(x – 1) km.
Therefore 20x + 25(x – 1) = 110
=> 45x = 135
=> x = 3.
So, they meet at 10 a.m.
See lessA train travelling at 48 kmph completely crosses another train having half its length and travelling in opposite direction at 42 kmph, in 12 seconds. It also passes a railway platform in 45 seconds. The length of the platform is
Answer: Option (A) 400 m Explanation: Let the length of the first train be x metres. Then, the length of the second train is x /2 metres. Relative speed = (48 + 42) kmph = 90 x (5/18) m/sec = 25 m/sec. Therefore [x + (x/2)]/25 = 12 or 3x/2 = 300 or x = 200. Therefore Length of first train = 200 m. LRead more
Answer: Option (A) 400 m
Explanation:
Let the length of the first train be x metres.
Then, the length of the second train is x /2 metres.
Relative speed = (48 + 42) kmph = 90 x (5/18) m/sec = 25 m/sec.
Therefore [x + (x/2)]/25 = 12 or 3x/2 = 300 or x = 200.
Therefore Length of first train = 200 m.
Let the length of platform be y metres.
Speed of the first train = 48 x (5/18) ( m/sec = 40/3 m/sec.
Therefore (200 + y) x( 3/40) = 45
=> 600 + 3y = 1800
=> y = 400 m.
See lessA train overtakes two persons walking along a railway track. The first one walks at 4.5 km/hr. The other one walks at 5.4 km/hr. The train needs 8.4 and 8.5 seconds respectively to overtake them. What is the speed of the train if both the persons are walking in the same direction as the train?
Answer: Option (D) 81 km/hr Explanation: 4.5 km/hr = 4.5 x (5/18) m/sec = 5/4 m/sec = 1.25 m/sec, and 5.4 km/hr = 5.4 x (5/18) m/sec = 3/2 m/sec = 1.5 m/sec. Let the speed of the train be x m/sec. Then, (x - 1.25) x 8.4 = (x - 1.5) x 8.5 => 8.4x - 10.5 = 8.5x - 12.75 => 0.1x = 2.25 => x =Read more
Answer: Option (D) 81 km/hr
Explanation:
4.5 km/hr = 4.5 x (5/18) m/sec = 5/4 m/sec = 1.25 m/sec, and
5.4 km/hr = 5.4 x (5/18) m/sec = 3/2 m/sec = 1.5 m/sec.
Let the speed of the train be x m/sec.
Then, (x – 1.25) x 8.4 = (x – 1.5) x 8.5
=> 8.4x – 10.5 = 8.5x – 12.75
=> 0.1x = 2.25
=> x = 22.5
Therefore Speed of the train = 22.5 x 18/5 km/hr = 81 km/hr.
See lessA train overtakes two persons who are walking in the same direction in which the train is going, at the rate of 2 kmph and 4 kmph and passes them completely in 9 and 10 seconds respectively. The length of the train is:
Answer: Option (B) 50 m Explanation: 2 kmph = 2 x (5/18) ( m/sec = 5/9 m/sec. 4 kmph = 4 x (5/18) m/sec = 10/9 m/sec. Let the length of the train be x metres and its speed by y m/sec. Then, x /(y-5/9) = 9 and x/(y-10/9) = 10. Therefore 9y - 5 = x and 10(9y - 10) = 9x => 9y - x = 5 and 90y - 9xRead more
Answer: Option (B) 50 m
Explanation:
2 kmph = 2 x (5/18) ( m/sec = 5/9 m/sec.
4 kmph = 4 x (5/18) m/sec = 10/9 m/sec.
Let the length of the train be x metres and its speed by y m/sec.
Then, x /(y-5/9) = 9 and x/(y-10/9) = 10.
Therefore 9y – 5 = x and 10(9y – 10) = 9x
=> 9y – x = 5 and 90y – 9x = 100.
On solving, we get: x = 50.
Therefore Length of the train is 50 m.
Two trains are running at 40 km/hr and 20 km/hr respectively in the same direction. Fast train completely passes a man sitting in the slower train in 5 seconds. What is the length of the fast train?
Answer: Option (C) 27(7/9) m Explanation: Relative speed = (40 - 20) km/hr =20 x (5/18) m/sec = 50/9 m/sec. Therefore Length of faster train = ( 50/9) x 5 m = 250/9 m = 27(7/9) m.
Answer: Option (C) 27(7/9) m
See lessExplanation:
Relative speed = (40 – 20) km/hr =20 x (5/18) m/sec = 50/9 m/sec.
Therefore Length of faster train = ( 50/9) x 5 m = 250/9 m = 27(7/9) m.
A train 108 m long moving at a speed of 50 km/hr crosses a train 112 m long coming from opposite direction in 6 seconds. The speed of the second train is:
Answer: Option (D) 82 km/hr Explanation: Let the speed of the second train be x km/hr. Relative speed = (x + 50) km/hr = (x + 50) x (5/18 )m/sec = (250 + 5x)/18 m/sec. Distance covered = (108 + 112) = 220 m. Therefore 220/((250+5x)/18) = 6 => 250 + 5x = 660 => x = 82 km/hr.
Answer: Option (D) 82 km/hr
Explanation:
Let the speed of the second train be x km/hr.
Relative speed = (x + 50) km/hr
= (x + 50) x (5/18 )m/sec
= (250 + 5x)/18 m/sec.
Distance covered = (108 + 112) = 220 m.
Therefore 220/((250+5x)/18) = 6
=> 250 + 5x = 660
=> x = 82 km/hr.
See lessTwo trains of equal lengths take 10 seconds and 15 seconds respectively to cross a telegraph post. If the length of each train be 120 metres, in what time (in seconds) will they cross each other travelling in opposite direction?
Answer: Option (B) 12 Explanation: Speed of the first train = 120/10 m/sec = 12 m/sec. Speed of the second train = 120/15 m/sec = 8 m/sec. Relative speed = (12 + 8) = 20 m/sec. Therefore Required time = (120 + 120)/20 sec = 12 sec.
Answer: Option (B) 12
Explanation:
Speed of the first train = 120/10 m/sec = 12 m/sec.
Speed of the second train = 120/15 m/sec = 8 m/sec.
Relative speed = (12 + 8) = 20 m/sec.
Therefore Required time = (120 + 120)/20 sec = 12 sec.
See lessTwo trains are running in opposite directions with the same speed. If the length of each train is 120 metres and they cross each other in 12 seconds, then the speed of each train (in km/hr) is:
Answer: Option (C) 36 Explanation: Let the speed of each train be x m/sec. Then, relative speed of the two trains = 2x m/sec. So, 2x = (120 + 120)/12 => 2x = 20 => x = 10. Therefore Speed of each train = 10 m/sec = 10 x (18/5) km/hr = 36 km/hr.
Answer: Option (C) 36
Explanation:
Let the speed of each train be x m/sec.
Then, relative speed of the two trains = 2x m/sec.
So, 2x = (120 + 120)/12
=> 2x = 20
=> x = 10.
Therefore Speed of each train = 10 m/sec = 10 x (18/5) km/hr = 36 km/hr.
See lessTwo goods train each 500 m long, are running in opposite directions on parallel tracks. Their speeds are 45 km/hr and 30 km/hr respectively. Find the time taken by the slower train to pass the driver of the faster one.
Answer: Option (B) 24 sec Explanation: Relative speed = = (45 + 30) km/hr = 75 x 5 /18 m/sec = 125/6 m/sec. We have to find the time taken by the slower train to pass the DRIVER of the faster train and not the complete train. So, distance covered = Length of the slower train. Therefore, Distance coRead more
Answer: Option (B) 24 sec
Explanation:
Relative speed = = (45 + 30) km/hr
= 75 x 5 /18 m/sec
= 125/6 m/sec.
We have to find the time taken by the slower train to pass the DRIVER of the faster train and not the complete train.
So, distance covered = Length of the slower train.
Therefore, Distance covered = 500 m.
Therefore Required time = 500 x (6/125) = 24 sec.
See lessHow many seconds will a 500 metre long train take to cross a man walking with a speed of 3 km/hr in the direction of the moving train if the speed of the train is 63 km/hr?
Answer: Option (B) 30 Explanation: Speed of the train relative to man = (63 - 3) km/hr = 60 km/hr = 60 x (5/18) m/sec = 50/3 m/sec. Therefore Time taken to pass the man = 500 x (3/50) sec = 30 sec.
Answer: Option (B) 30
See lessExplanation:
Speed of the train relative to man = (63 – 3) km/hr
= 60 km/hr
= 60 x (5/18) m/sec
= 50/3 m/sec.
Therefore Time taken to pass the man
= 500 x (3/50) sec
= 30 sec.