The Quantitative Aptitude Section of Success Bureau Study Material covers the complete syllabus and includes Often Asked Questions
( OAQs) in the Competitive Examinations .
Hence, you are advised to properly cram the contents . You should not waste time in learning out dated books .
Below is given a small Sample of the Study Material provided to the students .
A Fraction, whose Denominator is 100, is called the Percentage or Rate Percentage and the Numerator of the Fraction is Denoted by % .
For example, 25% means 25 out of 100 This can be expressed as 25 / 100 = 1/ 4
Similarly, 100% means 100 / 100 = 1.
(A) Multiply by 100 if you want to Show a Certain Number in % .
(B) Divide by 100 if you want to Remove % Sign from a Certain Number .
Examples : Q.1 2 / 10 as a rate per cent is ?
Solution : 2 / 10 x 100 = 20% .
Q.2 3.793 as a rate per cent is ?
Solution : 3.793 x 100 = 379.3 %
Q.3 20% = ?
Solution : 20 / 100 = 1 / 5
Q.4 3.768 % = ?
Solution : 3.768 / 100 = 0.03768
In Competitive Examinations, the Questions Based on the Following Relationship of A, B and C, are Often Asked :
A % of B = C |
In such problems, You are required to find out the Value of Any of the Three ( i.e. A, B or C ) on the basis of the Given Values of any Two .
These Problems can be Easily Solved in the following way :
A = C x 100 / B |
B = C x 100 / A |
C = A x B / 100 |
Examples : Q.1 Find out the value of X if X % of 200 is equal to 50 .
Solution : X = 50 x 100 / 200 = 25
Q.2 20 is what % of 80 or X % of 80 is 20 ?
Solution : X = 20 x 100 / 80 = 25 %
Q.3 40% of 600 is equal to what ?
Solution : Suppose, 40% of 600 = X . Hence , X = 40 x 600 / 100 = 240
Memories the following relationships given in the Chart below. It will help you in solving the percentage questions quickly :
CHART-1
5 % = 1/20 | 55 % = 11/20 |
10 % = 1/10 | 65 % = 13/20 |
15 % = 3/20 | 85 % = 17/20 |
20 % = 1/5 | 75 % = 3/4 |
25 % = 1/4 | 50 % = 1/2 |
35 % = 7/20 | 100 % = 1 |
40 % = 2/5 | 45 % = 9/20 |
From the above chart we can see that for obtaining 5% of a certain number, we have to divide the number by 20 and so on .
100 % = 1 | 200 % = two times of anything |
Similarly, | 25 % = 1 / 4 of anything |
20 % = 1 / 5 of anything | 10 % = 1 / 10 of anything |
100 % of 10 will be 10 x 1 = 10 | 200 % of 10 will be 10 x 2 = 20 |
400 % of 10 will be 10 x 4 = 40 | 50 % of 10 will be 10 x 1 / 2 = 5 |
25 % of 10 will be 10 x 1 / 4 = 25 | 10 % of 10 will be 10 x 1 / 10 = 1 |
Examples :
Q.1 5% of 80 = ?
Solution : 80 x 1/20 = 4
Q.2 20% of 400 = ?
Solution : 400 x 1/5 = 80
Q.3 35% of 900 = ?
Solution : 900 x 7/20 = 315
Q.4 12.5% of 200 = ?
Solution : 200 X 1/8 = 25
Q.5. Two numbers are respectively 20% and 40% more than a third number. What is the ratio of the two numbers ?
Solution : Suppose the third number is 100 .
Hence, the Ist and IInd numbers would naturally be 120 and 140 respectively. Ratio = 120 : 140 = 6 : 7.
Q.6. A Regiment lost in an engagement 25% of its men and still had 300 men left . What was the original number of men in the regiment ?
Solution : 75% ( or 3/4th ) of original men = 300 . Hence , Original men = 300 x 4/3 = 400
Q.7. The number of seats for admission for a vocational course is increased by 15% every year. If the number of students in 2017 is 800, what is the expected number of students in 2019 ?
Solution : The no. of seats increases by 15% ever year. So, 800 x 115 / 100 x 115 / 100 = 1058
Q.8. 30% of A’ s salary is equal to the 20% of 3/5th of B’ s salary. If B’s salary is Rs. 24,000/- , what is A’s salary ?
Solution : Suppose A’s salary is Rs. X.
Then, 3X / 10 = 1 / 5 x 3 / 5 x 24000/- ( 30% = 3/10 , 20% = 1/5 ) Or X = Rs. 9600/-
Q.9. In a library, 40% of the total number of books are in English, 80% of the rest in Hindi and the balance 300 books are in other languages. What is the total number of books in the library ?
Solution : Suppose total number of books = X
Hence, 40% of X + 80% of ( X – 40% ) + 300 = X Or 2X / 5 + 4 / 5 ( X – 2X / 5 ) + 300 = X Or X = 2500
Q.10. After deducting 20% from a certain sum and then 25% from the remainder, there are Rs.1200/- left . Find the original sum .
Solution : Suppose the original sum was Rs. X. After deducting 20%, 80% of X is left .
Then after deducting 25% of the remainder 75% of it would be left which is equal to Rs. 1200/-
The whole process can be shown like this : 4X / 5 x 3 / 4 = 1200 ( 80% = 4 / 5 , 75% = 3 / 4
Or X = Rs. 2000
The Quantitative Aptitude Section of Success Bureau Study Material covers complete syllabus and includes Often Asked Questions ( OAQs ) in the Competitive Examinations .
Hence, you are advised to properly cram the contents . You should not waste time in learning out dated books .
Above is given a small sample of the Study Material provided to the students .