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:

An agent, gets a commission of 2.5% on the sales of cloth. If on a certain day, he gets Rs. 12.50 as commission, the cloth sold through him on that day is worth

A) 300 B) 500
C) 700 D) 900
 
Answer & Explanation Answer: B) 500

Explanation:

Let the total sale be Rs. x.

 

Then, 2.5%. of x = 12.50

=> (25/100 * 1/100 * x) =  125/10

=> x = 500.

Report Error

View Answer Report Error Discuss

Filed Under: Percentage

29 18681
Q:

Two numbers are 20% and 30% less than the third number . How much percent is the second number less than first?

Answer

Let the third number be 100.


 


Then, the first number = 100 - 20 = 80 and second number = 100 - 30 = 70.


 


Difference between the first and second number = 80-70 = 10


 


\inline \therefore Required percentage = 1080 x 100% = 100/8 = 12.5%


 


 

Report Error

View answer Workspace Report Error Discuss

Subject: Percentage Exam Prep: Bank Exams

34 18591
Q:

In an examination, 34% of the students failed in Mathematics and 42% faiied in English. If 20% of the students failed in both the subjects, then the percentage of students who passed in both the subjects was :

A) 34 % B) 44 %
C) 54 % D) 64 %
 
Answer & Explanation Answer: B) 44 %

Explanation:

n (A) = 34, n (B) = 42, n (A   B) = 20.

 

So, n (A  U B) = n (A) + n(B) - n(A B) = 34 + 42 - 20 = 56.

 

Percentage failed in either or both the subjects = 56.

 

Hence, percentage passed = (100 - 66)% = 44%.

Report Error

View Answer Report Error Discuss

Filed Under: Percentage

27 18259
Q:

The ratio of earnings of A and B is 4:5. If the earnings of A increase by 20% and the earnings of B decrease by 20%, the new ratio of their earnings becomes 6:5. What are A's earnings?

A) Rs.22,000 B) Rs.27,500
C) Rs. 26,400 D) Cannot be determined
 
Answer & Explanation Answer: D) Cannot be determined

Explanation:
Report Error

View Answer Report Error Discuss

Filed Under: Percentage
Exam Prep: Bank Exams
Job Role: Bank PO

97 17970
Q:

A candidate got 35% of the votes polled and he lost to his rival by 2250 votes. How many votes were cast ?

A) 7500 B) 6200
C) 5600 D) 4700
 
Answer & Explanation Answer: A) 7500

Explanation:

Let the candidates be A & B
35%-----------A
65%-----------B

Difference of votes (65-35)% = 30%

=>          30% ------- 2250
Then for 100% -------- ?     => 7500

Report Error

View Answer Report Error Discuss

Filed Under: Percentage
Exam Prep: AIEEE , Bank Exams , CAT , GATE
Job Role: Bank Clerk , Bank PO

25 17418
Q:

The current birth rate per thousand is 32, whereas corresponding death rate is 11 per thousand. The net growth rate in terms of population increase in percent is given by :

A) 1.2 % B) 2.1 %
C) 3.1 % D) 1.3 %
 
Answer & Explanation Answer: B) 2.1 %

Explanation:

 Net growth on 1000 = (32 - 11) = 21. Net growth on 100 =(21/1000 * 100) %= 2.1%.

Report Error

View Answer Report Error Discuss

Filed Under: Percentage

18 16999
Q:

Abhinav scores 80% in physics and 66% in chemistry and the maximum marks of both the papers are 100. what percent does he score in maths which is of 200 marks, if he scores 80% marks in all the three subjects: 

A) 74% B) 84%
C) 87% D) 83%
 
Answer & Explanation Answer: C) 87%

Explanation:

80100 + 66100 + x200 = 320400

 

=>x = 174 =>    87%

Report Error

View Answer Report Error Discuss

Filed Under: Percentage

31 16021
Q:

While purchasing one item costing Rs. 400, I had to pay the sales tax at 7% and on another costing Rs. 6400, the sales tax was 9%. What percent of the sales tax I had to pay, taking the two items together on an average ?

A) 8 + 15/17 B) 2 + 13/17
C) 3 + 2/17 D) 5 + 13/12
 
Answer & Explanation Answer: A) 8 + 15/17

Explanation:

Total sales tax paid = 7% of Rs, 400 + 9% of Rs. 6400

                            =Rs. (7/100)*400 + (9/100)*6400 = Rs. (28 + 576) = Rs. 604. 

 

Total cost of the items = Rs. (400 + 6400) = Rs. 6800.

 

Required percentage =(604/6800*100) % = 81517%.

Report Error

View Answer Report Error Discuss

Filed Under: Percentage

28 15763