Percentage ( Aptitude )

per cent means " by a specified amount in or for every hundred." e.g. 10% means 10 parts of 100 parts.

 

Let a bank gives 4% rate of interest monthly. That means if you have saved 1000 rupees in this bank  it will give you 40 rupees monthly.

• 'X' percent of 'Y' means : ( X / Y ) × 100
• 'Y' percent of 'X' means : ( Y / X ) × 100

i.e. both are equal : X % Y = Y % X

Percentage Increase : Let 'x' amount of money is increased by 'p' percent. That means the final amount of money = x + ( p%x ) = x + [ ( p/x ) × 100 ]

e.g. 100 rupees is increased by 20% i.e. the money is now become :

100 + [ ( 20/100 ) × 100 ]= 120

Percentage Decrease : Unlike percentage increase the money after 20% decrease in 100 rupees should be : 

100 - [ ( 20/100 ) × 100 ] = 80

• What percent of 'X' is 'P' : [ ( P / X ) × 100 ] %
  
• percentage change in value  : [ ( change / initial value ) ×100 ] %
• If the price of a goods increases by X% , then the decrease in consumption should be [ r / ( 100 + X ) × 100 ]%.
• If the price of a goods decreases by X% , then the increase in consumption should be
  
  [ r / ( 100 - X ) × 100 ]%.
  

i.e. let we consume 10 rupees of sugar which is 2 k.g. . If the price of 1 k.g. sugar increases from 5 rupees to 10 rupees, then we have to consume 1 k.g. sugar so as not to increase our expenditure.

• Let the population of a town be 'P' and it increases r% per annum. Then population after n year
  
  = P × [ 1 + ( r/100) ]ⁿ
• and population before n year
  
  = P / [ 1 + ( r/100) ]ⁿ
• If the population decreases by r% per annum, then population after n year
  
  = P × [ 1 - ( r / 100) ]ⁿ
• population before n year
  
  = P / [ 1 - ( r / 100) ]ⁿ

    Quiz link below ⏬⏬⏬

    If you want to see all the aptitude quiz links click the button below .