Shortcuts in solving aptitude-6

TRAINS

General Concept:

(1) Time taken by a train x mt long in passing a signal poster a pole or a standing man = time taken by   the train to cover x mt

(2) Time taken by a train x mt long in passing a stationary object of length y mt = time taken by the train to cover x+y mt

(3) Suppose two trains or two bodies are moving in the same direction at u kmph and v kmph such that u > v then their relative speed is u-v kmph

(4)If two trains of length x km and y km are moving in opposite directions at u kmph and vmph,then time taken by the train to cross each other = (x+y)/(u+v) hr

(5) Suppose two trains or two bodies are moving in opposite direction at u kmph and v kmph then, their relative speed = (u+v) kmph

(6)If two train start at the same time from 2 points A & B towards each other and after crossing they take a & b hours in reaching B & A respectively then A's speed : B's speed = (b^1/2 :   a^1/2 )

To exercise some problems on trains visit here

RACES AND GAMES OF SKILLS

Races:

A contest of speed in running, riding, driving, sailing or rowing is called a Race

Race Course:

The ground or path on which contests are made is called a  race course

Starting Point:

The point from which a race begins is called starting point.

Winning point or goal:

The point set to bound a race is called a winning point.

Dead Heat Race:

If all the persons contesting a race reach the goal exactly at the same time, then the race is called a dead heat race.

Start:

Suppose A and B are two contestants in a race .If before the start of the race, A is at the starting point and B is ahead of A by 12 meters. Then we say that "A gives B a start 12 meters.

->To cover a race of 100metres in this case, A will have to cover 100m while B will have to cover 88m=(100-12)

->In a100m race 'A can give B 12m' or 'A can give B a start of 12m' or 'A beats B by 12m'means that while A runs 100m B runs 88m.

Games:

A game of 100m, means that the person among the contestants who Scores 100 points first is the winner.

If A scores 100 points while B scores only 80 points then we say That 'A can give B 20 points'.

To exercise some problems on races visit here