FACTS  AND  FORMULAE  FOR  PERCENTAGE  QUESTIONS

 

 

I.Concept of Percentage : By a certain percent , we mean that many hundredths. Thus x percent means x hundredths, written as x%.

To express x% as a fraction : We have , x% = x/100.

Thus, 20% = 20/100 = 1/5;     

48% = 48/100 = 12/25, etc.

To express a/b as a percent : We have, ab=ab×100% .

 

Thus, 14=14×100%=25%

   

 

II. If the price of a commodity increases by R%, then the reduction in consumption so as not to increase the expenditure is R100+R×100%

If the price of the commodity decreases by R%,then the increase in consumption so as to decrease the expenditure is R100-R×100%

 

 

III. Results on Population : Let the population of the town be P now and suppose it increases at the rate of R% per annum, then :

1. Population after n years = P1+R100n

 

2. Population n years ago =  P1+R100n

 

 

IV. Results on Depreciation : Let the present value of a machine be P. Suppose it depreciates at the rate R% per annum. Then,

1. Value of the machine after n years = P1-R100n

 

2. Value of the machine n years ago = P1-R100n

 

 

V. If A is R% more than B, then B is less than A by

R100+R×100%    

If A is R% less than B , then B is more than A by 

R100-R×100%  

Q:

If 4/5th of 6/7th of a number is 216, then 8/9th of that number will be

A) 179 B) 280
C) 160 D) 149
 
Answer & Explanation Answer: B) 280

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Q:

The list price (marked price ) of an article is Rs. 900 and is available at two successive discounts of 20% and 10% ; the selling price of the article,in rupees, is

A) 640 B) 648
C) 720 D) 738
 
Answer & Explanation Answer: B) 648

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Q:

The costs of daily ticket of local train is Rs 130 and Monthly Pass costs Rs 3091.40. If I buy the Monthly Pass and travel for 29 days in a month than I save (in percentage)?

A) 16 percent B) 18 percent
C) 15 percent D) 14 percent
 
Answer & Explanation Answer: B) 18 percent

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Q:

The number of trees in a town is 17640. If the numbers of trees increases annually at the rate of 5%, then how many trees were there 2 years ago?

A) 14000 B) 15000
C) 16000 D) 18000
 
Answer & Explanation Answer: C) 16000

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Q:

The bar chart given shows the sales of 3 types of cars in the Indian automotive industry over 4 years. All the sales figures have been shown in terms of 000 units.

What is the simple annual growth rate (in %) in the sales of SUV from 2009 to 2012?

A) 90 B) 100
C) 133.33 D) 150
 
Answer & Explanation Answer: C) 133.33

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Q:

If 3 dupatta is offered free on purchase of 6 dupattas priced Rs 1200 each what is the effective discount on each dupatta?

A) 25 percent B) 30 percent
C) 12.5 percent D) 33.33 percent
 
Answer & Explanation Answer: D) 33.33 percent

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Q:

Two baskets together have 640 oranges. If (1/5)th of the oranges in the first basket be taken to the second basket. The number of oranges in the first basket is

A) 800 B) 600
C) 400 D) 300
 
Answer & Explanation Answer: C) 400

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Q:

The population of a town is 350000. It increases annually at the rate of 20%. What will be the population after 2 years?

A) 490000 B) 497000
C) 504000 D) 508000
 
Answer & Explanation Answer: C) 504000

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