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:

The value of a machine depreciates at the rate of 20% per annum. If its present value is Rs 96000, then what was the value (in Rs) of the machine 2 years ago?

 

A) 138240   B) 134400  
C) 150000   D) 144000
 
Answer & Explanation Answer: C) 150000  

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3 447
Q:

If three successive discounts of 20%, 30% and 40% are given, then what will be the net discount (in percentage)?

A) 80 B) 87.6
C) 90 D) 66.4
 
Answer & Explanation Answer: D) 66.4

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2 445
Q:

38% of 250 is equal to

A) 95 B) 114
C) 76 D) 104.5
 
Answer & Explanation Answer: A) 95

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0 445
Q:

84% of a number is 105. The number is :

A) 120 B) 115
C) 112 D) 125
 
Answer & Explanation Answer: D) 125

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3 438
Q:

In an election between two candidates, the winning candidate got 70% of the valid votes and won by a majority of 9000 votes. If out of total votes polled 90% votes are valid, then what is the total number of votes polled?

 

A) 30000 B)  25000
C) 22500 D) 27000
 
Answer & Explanation Answer: B)  25000

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6 422
Q:

Weight of Ayush and Abhishek are in the ratio of 6:11. Abhishek's weight increases by 25% and total weight of Ayush and Abhishek both increases by 40%. If total weight becomes 119 kg, then wat is the weight (in kg) of Ayush after the increment?

A) 45.5 B) 30
C) 50.25 D) 47.75
 
Answer & Explanation Answer: C) 50.25

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2 418
Q:

56% of 250 is

A) 56 B) 140
C) 84 D) 112
 
Answer & Explanation Answer: B) 140

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5 404
Q:

32% of a number is 80. What is the number?

A) 260 B) 50
C) 40 D) 250
 
Answer & Explanation Answer: D) 250

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0 400