Tips to solve Interest Questions in SSC CGL Quantitative Aptitude

Updated On -

Jun 30, 2017

Shivani Tiwari

Content Curator

No competitive exam in banking and similar especially SSC CGL is complete without questions from Simple Interest (SI) and Compound Interest (CI). Since, the questions are more or less similar to that the coaching is done for so these questions take the least time and have an accuracy level of 90-100%.

• Important key to solving simple and compound interest related questions is to remember the formulae.
• To understand the question and applying the relevant formula and getting the correct answer is smooth ride.

Weightage over the years for Si and Ci

Topic / Year 2014 2015 2016 2017
Simple Interest 1 2 2-3 2-3
Compound Interest 1 2 2-3 2-3

Important Formulae for Si And Ci

The cost of borrowing money from bank is defined as Interest. It is of two types –

• Simple interest
• Compound interest

Simple interest – SI, is calculated only on the principal - P whereas,

Compound interest – CI that is calculated on the principal and on the accumulated interest of all earlier years i.e. interest on interest. This compounding effect on amount makes a big difference to the amount of interest that is payable on the principal.

Simple Interest is Denoted by Si

• Interest: denoted by I, is the money paid by the borrower to the lender for using money for specific period of time.
• Principle: denoted by P is the original amount borrowed.
• Time: denoted by n is the period for which the money has been borrowed.
• Rate of Interest: denoted by r is at which interest is calculated on the original sum.
• Amount: denoted by A is the sum of the principal plus the interest.

Simple Interest = Principal x Interest Rate * Term of the loan (Time of Loan)

SI = P x I x n/100 when interest rate is taken in percent.

A=P+SI

Compound Interest

CI = P [(1 + i)n – 1]

Where, P = Principal, I = annual interest rate %, and n = number of years (compounding periods).

The interest here is added to the principal at the end of every period to arrive at the new principal that becomes amount for the next period.
Example:

Let P- be principal borrowed for a period of I.
Amount at end of period n=1 is
A= P (1+r/100)
Henceforth,
New Principal that commences at the beginning of period II will be A i.e. P (1+r/100) = P*R where R=(1+r/100).

Challenges Faced by Students in SSC CGL

It is essential to follow study tactics and tips in order to strengthen overall prowess over the Quantitative Aptitude Section.

• Time Management is of utmost importance for any competitive exams. Henceforth, there is not much time to spend on making calculations.
• For calculating faster, you should remember all basics like tables, square, cubes and square roots.
• Basics First is the trick of trade so that time saved here can be used for complicated problems.
• On starting the preparation never try to solve questions by adopting shortcut methods.
• Always memorize the basic theories and related formulas of the chapters.
• If your basics are clear everything becomes easier to solve questions.
• Create a Summary of Notes.
• Make a brief version of your class notes in shape of summary notes.
• Spot all the key terms and concepts and to make sure to have understood them well.
• You can also identify key terms and basic concepts by paying attention to all that has been emphasized during class, textbooks and course syllabus.
• Maintain and plan for each and every day to practice topics.
• Try to devote minimum of 3 hours for practice of quant on daily basis.
• Once done with all basics, practice to max with sample questions of previous years.
• Previous Years Papers is the best practice to have your mind running in right direction.
• Make use of shortcut methods in the right way
• Make sure of remembering all short tricks for the Quant section as it can be a lifeline and also time saver for all competitive exams.
• This section can be easy for you to attempt by applying right tricks.
• Learn to calculate at Faster Pace.
• Easier questions calculate in your mind, but you need to divide complex calculations into separate parts and solve it on paper.
• Only practice can help mastering technique of calculating in mind, that can help in complex problems.

Types of Questions Asked for Si, Ci And Misc. and Sample Questions

Question 1: Kamal lent out INR 60000. Out of these some part at 5% and remaining at 4% at simple interest. If total annual interest is INR 2560. What is the amount at 4%?

A) INR 40000
B) INR 44000
C) INR 30000
D) INR 45000

Question 2: The difference between the compound interest and the simple interest on a certain sum at 12% p.a. for two years is INR 90. What will be the value of the amount at the end of 3 years?
A) 9000
B) 6250
C) 8253
D) 8780.8

Question 3: Find the compound interest on INR 15,625 for 9 months at 16% per annum compounded quarterly.

A) INR 1851
B) INR 1941
C) INR 1951
D) INR 1961

Question 4: A sum of money at compound interest amounts to thrice itself in 3 years. In how many years will it be 9 times itself?

A) 9
B) 27
C) 6
D) 3

Question 5: Find the compound interest on INR 12450 for 9 months at 12% per annum compounded quarterly
A) INR 1154.45
B) INR 1125.18
C) INR 1198.72
D) INR 1164.32

Recommended Study Material for SI and CI

For the simple and compound interest, one can refer to NCERT books of class IX to XII. These are scoring chapters so make sure to practice and score.

Name of the Book Author’s Name
Quantitative Aptitude R S Aggarwal
SSC for Math solved papers from 1997
Quicker Math M Tyra