Practice MCQ Questions and Answer on Speed Time and Distance
351.
In covering a distance of 30 km, Abhay takes 2 hours more than Sameer. If Abhay doubles his speed, then he would take 1 hour less then Sameer. Abhay's speed (in km/hr) is :
(A) 5
(B) 6
(C) 6.25
(D) 7.5
Solution:
In these type of questions go through options to save your valuable time : Option (A) Abhay's speed = 5 km/hr Abhay's time = = 6 hr Sameer's time = 6 - 2 = 4 hr Abhay's new time : = = 3 hr Hence option (A) is correct as it satisfies all the conditions.
352.
A thief running at 8 km/hr is chased by a policeman whose speed is 10 km/hr. If the thief is 100 metres ahead of the policeman, then the time required for the policeman to catch the thief will be :
(A) 2 minutes
(B) 3 minutes
(C) 6 minutes
(D) 10 minutes
Solution:
Relative speed = (10 - 8) km/hr = 2 km/hr Required time = Time taken to cover 100 m at relative speed :
353.
A car goes 10 meters in a second. Find its speed in km/hour.
A train travelling at 48 kmph crosses another train, having half of 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 railway platform is:
(A) 200m
(B) 300m
(C) 350m
(D) 400m
Solution:
Let the length of the train traveling at 48 kmph be 2x meters. And length of the platform is y meters.
355.
A postman goes with a speed of 36 km/h what is the speed of postman in m/s?
(A) 4.5 m/s
(B) 6 m/s
(C) 5 m/s
(D) 10 m/s
Solution:
Speed = 36 km/h = = 10 m/s
356.
Two buses start from a bus terminal with a speed of 20 km/h at interval of 10 minutes. What is the speed of a man coming from the opposite direction towards the bus terminal if he meets the buses at interval of 8 minutes?
(A) 3 km/h
(B) 4 km/h
(C) 5 km/h
(D) 7 km/h
Solution:
Let Speed of the man is x kmph. Distance covered in 10 minutes at 20 kmph = distance covered in 8 minutes at (20 + x) kmph. Or, Or, 200 = 160 + 8x Or, 8x = 40 Hence, x = 5kmph. Detailed Explanation: A _____________M_______________B A = Bus Terminal. B = Let meeting point of first bus and the man and this distance is covered by Bus in 10 minutes. I.e. Distance A to be is covered first bus in 10 min. As AB distance can be covered by second bus in 10 minutes as well. Distance Covered by Bus in 10 min = AB = = km. Now, M is the Meeting Point of Second Bus with Man. Man covered distance B to M in 8 minutes. Now, Relative distance of both Man and Bus will be same as both are traveling in opposite direction of each other. Let Speed of the man = x kmph. Relative speed = 20 + x To meet at Point M, bus and Man has covered the distance (AB) in 8 minutes with relative speed. And Same AB distance is covered by bus in 10 minutes. Thus, Distance covered in 8 minutes with relative speed (20 + x) kmph = distance covered by bus in 10 minuted with speed 20 kmph.
357.
A train passes two persons walking in the same direction at a speed of 3 km/hr and 5 km/hr respectively in 10 seconds and 11 seconds respectively. The speed of the train is :
(A) 28 km/hr
(B) 27 km/hr
(C) 25 km/hr
(D) 24 km/hr
Solution:
Let the train's speed = x km/hr When train will cross a man then it covers only its length. Note : Products of time × speed is always subtracted if both the men are running in the same direction and the products of time × speed is added only if the men are running opposite direction. ⇒ Here train's direction is not considered. But attention please ⇒ Always divided by the difference of time.
358.
A constable is 114 metre behind a thief. The constable runs 21 metres per minute and the thief runs 15 metres in a minute. In what time will the constable catch the thief ?
(A) 19 min
(B) 18 min
(C) 17 min
(D) 16 min
Solution: Time taken to catch the thief : = min = 19 min
359.
P and Q are 27 km away. Two trains with speed of 24 km/hr and 18 km/hr respectively start simultaneously from P and Q and travel in the same direction. They meet at a point R beyond Q. Distance QR is :
(A) 126 km
(B) 81 km
(C) 48 km
(D) 36 km
Solution:
Relative speed = 24 - 18 = 6 km/hr Time required by faster train to overtake slower train : = = hr ∴ Distance between Q and R : = 18 × = 81 km
360.
A man performs of the total journey by rail, by bus and the remaining 6.5 km on foot. His total journey is :