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 60% of a number is added to 60, then the result is equal to the number itself. What is the number?

 

A) 150   B) 120  
C) 100   D) 180  
 
Answer & Explanation Answer: A) 150  

Explanation:
Report Error

View Answer Report Error Discuss

Filed Under: Percentage
Exam Prep: Bank Exams

4 29934
Q:

Entry fee in an exhibition was Rs. 1. Later, this was reduced by 25% which increased the sale by 20%. The percentage increase in the number of visitors is :

A) 20 % B) 40 %
C) 60 % D) 80 %
 
Answer & Explanation Answer: C) 60 %

Explanation:

Let the total original sale be Rs. 100. Then, original number of visitors = 100.

New number of visitors  =  120/0.75 = 160.

Increase % = 60 %.

Report Error

View Answer Report Error Discuss

Filed Under: Percentage

95 28563
Q:

In a City, 35% of the population is composed of migrants, 20% of whom are from rural areas. Of the local population, 48% is female while this figure for rural and urban migrants is 30% and 40% respectively. If the total population of the city is 728400, what is its female population ?

A) 324138 B) 349680
C) 509940 D) None of these
 
Answer & Explanation Answer: A) 324138

Explanation:

Total Population = 728400

 

Migrants = 35 % of 728400  =  254940

 

local population = (728400 - 254940) = 473460.

 

Rural migrants = 20% of 254940 = 50988

 

Urban migrants = (254940 - 50988) = 203952

 

Female population = 48% of 473460 + 30% of 50988 + 40% of 203952 = 324138                        

Report Error

View Answer Report Error Discuss

Filed Under: Percentage

44 27334
Q:

If 3/5 of x is equal to 4/9 of y, then what is the ratio of x and y?

 

 

A) 11 : 15 B) 15 : 23
C) 20 : 27 D) 14 : 25
 
Answer & Explanation Answer: C) 20 : 27

Explanation:
Report Error

View Answer Report Error Discuss

Filed Under: Percentage
Exam Prep: Bank Exams

7 27181
Q:

What percent decrease in salaries would exactly cancel out the 20 percent increase ?

A) (16 + 2/3) % B) (15 + 2/3)%
C) (14 +1/3)% D) (13 + 4/5)%
 
Answer & Explanation Answer: A) (16 + 2/3) %

Explanation:

Let the orginal salary = Rs. 100. New's salary = Rs.120.

Decrease on 120 = 20. Decrease on 100 = [(20/120)*100]% = (16 + 2/3) %. 

Report Error

View Answer Report Error Discuss

Filed Under: Percentage

55 27145
Q:

Read the data given below and answer the questions based on it.

 

In the CBSE Board exams last year, 53% passed in Biology, 61% percent passed in English, 60% in Social studies, 24% in Biology and English, 35% in English and social studies, 27% in Biology and social studies and 5% in none.

 

What is the percentage of students who passed in all subjects?

A) 8 B) 12
C) 7 D) 10
 
Answer & Explanation Answer: C) 7

Explanation:
Report Error

View Answer Report Error Discuss

Filed Under: Percentage
Exam Prep: Bank Exams

4 27074
Q:

The diference of two numbers is 20% of the larger number, if the smaller number is 20, then the larger number is :

A) 15 B) 25
C) 35 D) 45
 
Answer & Explanation Answer: B) 25

Explanation:

Let the large number be x.

Then x - 20 = 20x/100

=> x - x/5 = 20  => x = 25.

Report Error

View Answer Report Error Discuss

Filed Under: Percentage

51 26034
Q:

Read the data given below and answer the questions based on it.

 

In the CBSE Board exams last year, 53% passed in Biology, 61% percent passed in English, 60% in Social studies, 24% in Biology and English, 35% in English and social studies, 27% in Biology and social studies and 5% in none.

 

What is the ratio of percentage of students who passed in Biology and Social Studies but not English in relation to the percentage of students who passed in Social Studies and English but not Biology?

A) 5:7 B) 7:5
C) 4:5 D) 5:4
 
Answer & Explanation Answer: A) 5:7

Explanation:
Report Error

View Answer Report Error Discuss

Filed Under: Percentage
Exam Prep: Bank Exams

2 25793