Aptitude - Time and Distance
6.
An athlete runs 200 metres race in 24 seconds. His speed is :
Answer
Speed = 20024 m/sec =
20024 x 185 
kmph = 30 kmph
Answer :
Option DExplanation :
Speed = 20024 m/sec =
20024 x 185 kmph = 30 kmph 7.
A certain distance is covered at a certain speed. If half of this distance is covered in double the time, the ratio of the two speeds is :
Answer
Let x km be covered in y hrs. Then, 1st speed = xy kmph
Again, x2 km is covered in 2y hrs.
∴ New speed = x2 x 12y kmph = x4y kmph
Ratio of speeds = xy : x4y = 1 : 14 = 4 : 1
Answer :
Option AExplanation :
Let x km be covered in y hrs. Then, 1st speed = xy kmph
Again, x2 km is covered in 2y hrs.
∴ New speed =
x2 x 12y kmph = x4y kmphRatio of speeds = xy : x4y = 1 : 14 = 4 : 1
8.
A man covers half of his journey at 6 kmph and the remaining half at 3 kmph. His average speed is
Answer
Time and Distance Speed = 2xy (x + y) kmph = 2 x 6 x 3 (6 + 3) kmph = 4 kmph
Answer :
Option CExplanation :
Time and Distance Speed = 2xy (x + y) kmph = 2 x 6 x 3 (6 + 3) kmph = 4 kmph
9.
Excluding stoppages, the speed of a bus is 54 kmph and including stoppages, it is 45 kmph. For how many minutes does the bus stop per hour ?
Answer
Due to stoppages, it covers 9 km less per hour.
Time taken to cover 9 km = 954 x 60 min = 10 min
Answer :
Option BExplanation :
Due to stoppages, it covers 9 km less per hour.
Time taken to cover 9 km =
954 x 60 min = 10 min 10.
If a student walks from his house to school at 5 kmph, he is late by 30 minutes. However, if he walks at 6kmph, he is late by 5 minutes only. The distance of his school from his house is :
Answer
Let the required distance be x km. Then,
x5 − x6 = 2560 [Difference between two times is 25 min]
⇒ 12x − 10x = 25 ⇒ 2x = 25
⇒ x = 12.5 km
Answer :
Option DExplanation :
Let the required distance be x km. Then,
x5 − x6 = 2560 [Difference between two times is 25 min]
⇒ 12x − 10x = 25 ⇒ 2x = 25
⇒ x = 12.5 km
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