__PERCENTAGES__

1. If x% is deducted on tax and y% of the remaining is spent on education and still there is a balance, the formula is :-

Balance * [ 100/(100-x) ] * [ 100/(100-y) ] * [ 100/(100-z) ] |

2. The population of a town is 'P'. It increased by x% during I

^{st}year, increased by y% during II

^{st}and again increased by z% during I

^{st}. The population after 3 years will be,

P * [ (100+x)/100 ] * [ (100+y)/y ] * [ (100+z)/100 ] |

3.% of effect

(i) Inc of x% Dec of x% x-y-[(x*y)/100]

(ii) Inc of x% Inc of y% (x+y)+[(x*y)/100]

(iii) Dec of x% Inc of y% [-x^{2}/100]

(iv) Dec of x% Dec of y% (-x-y)+[(x*y)/100]

(v) Inc of x% Dec of x% [-x^{2}/100]

(vi) Inc of x% Inc of x% 2*x+[x^{2}/100]

4. (i) If the sides of the traingle,rectangle,square,circle,rhombus etc is increased by x%.Its area is increased by

2x+(x ^{2}/100) |

(ii)If decreased x%.Its ares is decreased by,

-2x+(x ^{2}/100) |

5. In an examination x% failed in Hindi and y% failed in Science, if z% of the candidates failed in both of the subjects. The percentage of students who passed in both of the subjects is,

100-(x+y-z) |

6. If A's income is r% more than B's income, the B's income is less than A's income by

(r/100+r) * 100% |

7.If A's income is r% less than B's income, then B's income is more than A's income by

(r/100-r) * 100 |

8. (i)If the price of comodity increases by r% then reduction in consumption so as not to increase the expenditure is

(r/100+r) * 100 |

(ii)If the price of comodity decreases by r% then,

(r/100-r)*100 |

9.If the population of town (or) length of a tree is 'p' and its annual increase is r% then,

(i)populaton (or) length of a tree after 'n' years is,

p[1+(r/100)] |

(ii)population (or) length of a tree 'n' years ago is,

p/[1+(r/100) ^{n}] |

10.If the population of town (or) value of a machine is 'p' and annual decrease is r% then,

(i)populaton (or) value of machine after 'n' years is,

p[1-(r/100) ^{n}] |

(ii)population (or) value of a machine 'n' years ago is,

p/[1-(r/100) ^{n}] |

11.If 'A' is x% of 'C' and 'B' is y% of 'C' then 'A' is

(x/y) * 100% |

of 'B'.

12. If two values are respectively x% and y% more than a third value, then the first is

[(100+x) / (100+y)] * 100% |

of second

13.Total no.of votes =

(Difference in votes/Difference in %) * 100 |

14.Maximum marks =

[(pass marks/pass %) * 100] |

15.Total marks =

(Difference in marks / Difference in %)*100 |

16. (i)Reduced rate =

[(Amount/Quantity more) * (Reduction % /100)] |

(ii)Original rate (or) previous rate =

[(Amount/Quantity more) * (Reduction % /100-reduction%)] |

17. (i)Increased rate =

[(Amount/Quantity less) * (increase % /100)] |

(ii)Original rate (or) previous rate =

[(Amount/Quantity less) * (Increase % /100-increase%)] |

18. If the numeratorof fraction is increased by x% and its denominator is diminished by y% ,the value of the fraction is A/B.Then the original fraction is,

**(A/B) * [(100-y) / (100+x)]**

## 1 comment:

Very Useful, Thanks a Ton ^_^

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