Percentage Part -1

Percentage Part -1 

 
Rule : If x % of a quantity is taken by the first person, y % of the remaining quantity is taken by second person and z % of the remaining is taken by third person. If P amount is left in the balance, then original amount Q will be :-



Rule : If x % of a quantity is added, again y % of the increased quantity is added, again z % of the increased quantity is added, now it becomes P then the original quantity Q is given by :

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Ex. After deducting 20 % from a certain sum and then 25 % from the remainder, there is Rs. 6000 left Find the original sum ?

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Rule : If P is the original population of a town and annual increase is r % then Population after one year will be :

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Rule : If population of a town is P. It increases by x % during first year, increases by y % during second year and again increases by z % during the third year . Population after 3 years will be :

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Rule : If population of a town is P. It decreases by x % during first year, increases by y % during second year and again increases by z % during the third year . Population after 3 years will be

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Rule : If P is the original population of a town and annual increase is r % then Population after n years will be

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Ex. If During first year population of a town decreased by 10 %, second year population increased by 10 % . If the population at the end of second year was 9900, find the population at the beginning of the first year ?

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Ex. How many kg of pure salt must be added to 50 of 4 % solution of salt and water to increase it to a 10 % solution ?

Solution :
 

Let, x kg of pure salt be added to increase it to 10 % of solution, by rule of allegation,

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Ex. In an election a candidate who gets 84 % of votes is elected by majority of 476 votes. What is the total number of votes polled ?

Solution : Let the total number of votes polled be x.

Also votes gained by other candidates= ( 100 - 84 ) % of x = 16 % of x

Now, we can write as 84 % of x - 16 % of x = 476

so, x = 700