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Important Formula: Time and Distance,Problem on Trains,Boats & Streams



Quantum Aptitude is the first section in pH test. It Contains 20 questions from various Aptitude topics. All the important formulas are printed in the question paper. But you need to study more topics to crack the test. In this post covers some important topics and tips to solve Aptitude question.


Important Formula:

Speed      =   Distance / Time
Time        =   Distance / speed
Distance   =   speed * time
1 km/hr    =    518ms
1 m/s       =    185Kmhr
If the ratio of the speed of A and B is a:b,then the ratio of the time taken by them to cover the same distance is 1a:1b or b:a

Suppose  a  man  covers  a  distance  at  x  km/hr  and  an  equal  distance  at  y km/hr, then the AVERAGE SPEED during the whole journey is (2xy/x+y) km/hr

Out of time, speed and distance we can compute any one of the quantities when we happen to know the other two. For example, suppose we drive for 2 hours at 30 miles per hour, for a total of 60 miles. 

If we know the time and the speed, we can find the distance:
2 hour * 30 mileshour=60 miles
If we know the time and the distance, we can find the speed:
60 miles2 hours=30mileshour

Distance is directly proportional to Velocity when time is constant:

Train Problems:

The basic equation in train problem is the same
Speed=Distance/Time

The following things need to be kept in mind while solving the train related problems.
  • When the train is crossing a moving object, the speed has to be taken as the relative speed of the train with respect to the object.
  • The distance to be covered when crossing an object, whenever trains crosses an object will be equal to: Length of the train + Length of the object
Boats & Streams:

Let U= Velocity of the boat in still water
V=Velocity of the stream.

While moving in upstream, distance covered,   S=(U−V)T
In case of downstream, distance covered ,    S=(U+V)T

Clock:

For clock problems consider the clock as a circular track of 60km.
Min. hand moves at the speed of 60km/hr (think min. hand as a point on the track) and hour hand moves at 5km/hr and second hand at the speed of 3600 km/hr.
Relative speed between HOUR hand and MINUTE hand = 55

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