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:

Find 150% of X, if X is the least number which when divided by 6, 7, 8, 9 and 12 leaves remainders 2, 3, 4, 5 and 8 respectively.

A) 750 B) 500
C) 1000 D) 1200
 
Answer & Explanation Answer: A) 750

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Q:

The marked price of a ceiling fan is Rs. 1200 and the shopkeeper allows a discount of 5 % on it. Then selling price of the fan is

A) Rs. 1410 B) Rs. 1400
C) Rs. 1140 D) Rs. 1104
 
Answer & Explanation Answer: C) Rs. 1140

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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:

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:

The marked price of a sofa set is Rs 4800 which is sold at Rs 3672 at two successive discounts. If the first discount is 10%, then what will be the second discount (in %)?

A) 13 B) 15
C) 14 D) 17
 
Answer & Explanation Answer: B) 15

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Q:

A carpenter can build a cupboard in 64 hours. After 16 hours he takes a break. What fraction of the cupboard is yet to be built?

A) 0.6 B) 0.75
C) 0.2 D) 0.8
 
Answer & Explanation Answer: B) 0.75

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Q:

Rs 11,550 has to be divided between X, Y & Z such that X gets 4/5 of what Y gets and Y gets 2/3 of what Z gets. How much more does Z get over X (in Rs)?

A) 7200 B) 1800
C) 1390 D) 2450
 
Answer & Explanation Answer: D) 2450

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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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