Speed, Time and Distance
- A train starts from A at 7 a.m. towards B with speed 50 km/h. Another train starts from B at 8 a.m. with speed 60 km/h towards A. Both of them meet at 10 a.m. at C. The ratio of the distance AC to BC is
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AC = Distance covered by train starting from A in 3 hours
= 50 × 3 = 150 km
BC = Distance covered by train starting from B in 2 hours
= 60 ×2 = 120 km
∴ AC : BC = 150 : 120 = 5 : 4Correct Option: B
AC = Distance covered by train starting from A in 3 hours
= 50 × 3 = 150 km
BC = Distance covered by train starting from B in 2 hours
= 60 ×2 = 120 km
∴ AC : BC = 150 : 120 = 5 : 4
- Two trains started at the same time, one from A to B and the other from B to A. If they arrived at B and A respectively 4 hours and 9 hours after they passed each other, the ratio of the speed of the two trains was
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Required ratio of the speed of two trains = √9 √4 = 3 or 3 : 2 2 Correct Option: B
Required ratio of the speed of two trains = √9 √4 = 3 or 3 : 2 2
- Two trains, of same length, are running on parallel tracks in the same direction with speed 60 km/hour and 90 km/hour respectively. The latter completely crosses the former in 30 seconds. The length of each train (in metres) is
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When two trains cross each other, they cover distance equal to the sum of their length with relative speed.
Let length of each train = x metre
Relative speed = 90 – 60
= 30 kmph= 
30 × 5 
m/sec. 18 = 25 m/sec. 3 ∴ 2x = 30 25 3 ⇒ 2x = 30 × 25 3
⇒ 2x = 250
⇒ x = 125 metresCorrect Option: A
When two trains cross each other, they cover distance equal to the sum of their length with relative speed.
Let length of each train = x metre
Relative speed = 90 – 60
= 30 kmph= 30 × 5 m/sec. 18 = 25 m/sec. 3 ∴ 2x = 30 25 3 ⇒ 2x = 30 × 25 3
⇒ 2x = 250
⇒ x = 125 metres
- Three cars travelled distance in the ratio 1 : 2 : 3. If the ratio of the time of travel is 3 : 2 : 1,
then the ratio of their speed is
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Required ratio = 1 : 2 : 3 3 2 1 = 1 : 1 : 3 3 1 × 3 : 1 × 3 : 3 × 3 3 
∴ Speed = Distance 
Time
= 1 : 3 : 9Correct Option: B
Required ratio = 1 : 2 : 3 3 2 1 = 1 : 1 : 3 3 1 × 3 : 1 × 3 : 3 × 3 3 ∴ Speed = Distance Time
= 1 : 3 : 9
- A and B run a 5 km race on a round course of 400 m. If their speed are in the ratio 5 : 4, the
number of times, the winner passes the other, is
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The winner will pass the other, one time in covering 1600m.
Hence, the winner will pass the other 3 times in completing 5km race.Correct Option: C
The winner will pass the other, one time in covering 1600m.
Hence, the winner will pass the other 3 times in completing 5km race.
