Free Online Preparation for CAT 2009 with Minglebox eCAT Prep. Cover basic concepts of Time and Distance under Quantitative Aptitude for MBA Entrance Exam Preparation with Study material, solved examples and tests prepared by CAT coaching experts.
Speed is the rate at which distance is covered by a moving body these speed
's' = or
s =
if speed is constant then
if distance is constant then
if time is constant then
Average speed. If a body cover half of the distance 'd' it a speed of and the half at speed then average speed is given by
= =
The time taken by a train of length 'l' moving with speed 's' to pare a pole is
=
Time taken by train of length 'l' moving with speed 's' to completely pare a platform of
length 'd' =
Time taken by strain of length 'l' moving with speed to par another train of length 'd' moving with speed in the direction (provided
) =
Time taken by a train, of length l, and moving with speed to pan another train of length 'd' moving with in the opposite direction
If person covers a certain distance 'd' moving speed and taking time , then the person covers the same distance moving at speed
and taking time then
If two persons X and Y start at the same time in opposite direction from two places and arrive at their respective destination in x an y hours later after having met on their on their way then
If speed of boat, in still water is 'a' (m/s) then speed of boat in going down stream in a river which is following at 'b' (m/s) is (a+b) m/s. Hence if a boat cover a certain distance 'd' downstream and then reruns it to its staring point covering the same distance 'd' then
If 2 persons say a,b start running a race on a circular track, then the faster runner (say A) will be together with the slower runner for the
first time when faster runner has gained one complete length of the track or round over the slower runner.
Question
2boats A and B start from point P at the same constant speed of 15 km/hr in still water . Boat A goes to Q, where boat B goes till R, which is equidistant from P and Q and returns to P. If the time taken by boat A is 1.5 times that of B, what is the speed of the current.

10 k mph

7.5 k mph ,

5k mph

Data insufficient
Solution
If the total distance between P and Q be '2D' km . Boat A has taken more time , the direction of the current must be form Q to P if the speed of the current must be X k mph then
Time taken by A =
Time taken by B =
Given
Solving we get x = 7.5 k mph have option 2 is the right option.
Question
A car covers half the half distance at speed 60kmph and another half of the distance at speed 30kmph . Find the average speed of the car for the whole journey?
Solution
If total distance be '2d' then time taken to cover the first half of the journey , =
and time taken to cover the second half of the journey =
Therefore total time taken =
Avg .Speed = =
Question
A car cover travels for half the time of the journey at speed 60kmph and another half of the time at 30kmph. Find the average speed of the car for whole journey?
Solution
Let the total time taken in for the journey be '2t' then distance covered in firat half of the journey = and distance covered in
second half of the journey
Average speed =
Hence average speed of for the whole journey = 45kmph
Question
Two persons A and B walk from X to Y a distance of 27 k at 5 km/hr and 7 km/hr respectively. B reaches Y and immediately turns back meeting A at Z. What is the distance from X to Z ?

25 km

22.5 km

24 km

20 km
Solution
Let the distance from X to Z be 'a' km then time taken by X to cover distance XZ is same as time taken by B to cover distance XY – YZ = 27 + 27a
Time Taken by A to cover XZ distance XZ =
Time taken by B to cover distance XY – XZ =
solving we get, a = 22.5 km
hence answer is option (2)
bappadittya : good
dhanraj77115 : oops atul u have to find avrage speed different distance is not given distance will b same as it consider as d
dhanraj77115 : average speed formula is correct; atul, u have learnt same bt another method formula
this formula is more simple to calculate average
vani9719 : yeah,anki is true
suresh3302 : In the final question.....together A & B will travel a distance of 54 which will be covered by A & B in the ration 5 : 7.
Now distance XZ is nothing but the share of A which will be 5/12 (54) = 22.5
ankita7231 : ankitapls include some toughest problems also
mayur3839 : add some more practise paper.....bt overall gud
baljinder874 : gud
atul2777 : 1 mistake in the formula:
Average speed. If a body cover half of the distance 'd' it a speed of and the half at speed then average speed is given by
total dist/total time= 2d/{(d1/s1)+d2/s2}
madydilse : please check the tests there are some mistakes in the questions...