Quantitative Aptitude Notes Part 3(PERCENTAGE)

CHAPTER-3

PERCENTAGE

What is percentage?
Percentage is a fraction or a numerical expression or a ration with 100 assumed as denominator. So we can represent 1 percentage as 1%.

Points to be remember-

 

  • 1 = 100%
  • 1/2 = 50%
  • 1/3 = 33%
  • 1/4 = 25%
  • 1/5 = 20%
  • 1/6 = 16%
  • 1/7 = 14%
  • 1/8 = 12%
  • 1/9 = 11%
  • 1/10 = 10%
  • 1/11 = 9%
  • 1/12 = 8%
  • 1/13 = 7%
  • If the price of a commodity increases by R%,then the reduction in consumption as not to increase the expenditure is =%
  • If the price of a commodity decreases by R%,then the increase in consumption as not to decrease the expenditure is= %.

 

  • Let the population of a town be P now and suppose it increases at the rate of R% per annul, then:
  • Population after n years =P (1+R/100)n
  • Population n years ago =
  • Let the present value of a machine beP. Suppose it depreciates at the rate of R% per annul, then :
  • Value of the machine aftern years =P(1-R/100)n 
  • Value of the machinen years ago =
  • IfA is R% more than B, then is less than A by=%
  • IfAis R% less than B, then is more than by= %.

 

 

Percentage Type1 Shortcut Tricks
Example:
If the difference between 45% of a number and 3/5th of that number is 18. What is the number?
Solution:
Let the number be a .
Then a x 45% – a x 3/5 = 18
a x 45% – a x 60% = 18 ∴( 60% = 3/5 )
a x 15% =18
a = 100×18 = 1800/15 = 120
Tricks:
we know 3/5 = 30%
45% – 30% = 15 %
15% = 18 = 120

 

Percentage Type2 Shortcut Tricks
Example:
Sahil work in shop and his 30% of income is  Rs.1800 .Find the 65% of his income and also find the 1 / 5 of Sahil’sincome.

  • Solution:30% = 1800 So, 65% = 1800 x 65 / 30 = 3900
  • Shortcut Trick:1800 x 65 / 30 = 3900.

 

Example:
Raj spend his money from his saving in different way that is he spends 30% on travel,10% on food,15% on wages and 22% on purchase a bike and after that all expenditure he saved 4600.Find the how much he spent on bike.
Solution: Let the total income of Raj=X.

then total expenditure from income = X x (30%+10%+15%+22%)=>X x 77%

Total savings= X x 23%
X = 4600 x 100 / 23 = 20000 and expenditure on Bike = 22% so, 20000 x 22 / 100 = 4400.

Shortcut Tricks
The total income as 100% so, (100% – 30%+10%+15%+22%) = 77% and now (100% – 77%) = 23%
Bike Expenditure is now 4600 x 22 / 23 = 4400.

 

 

Example:
Sanjay got 88 marks in Hindi , 81 marks in Science , 74 marks in Maths , 68 marks in Social Science and 57 marks in History . The maximum marks of each subject are100. How much overall percentage of marks did he get?
Solution: Percentage = 368 x 100 / 500 = 73.6

 

 

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