CAT 2025 Lesson : Interest & Growth - Concepts & Cheatsheet

Note: The video for this module contains a summary of all the concepts covered in the Interest & Growth lesson. The video would serve as a good revision. Please watch this video in intervals of a few weeks so that you do not forget the concepts. Below is a cheatsheet that includes all the formulae but not necessarily the concepts covered in the video.

7. Cheatsheet

1

) Simple Interest (SI)

= \dfrac{pnr}{100}

A = p + \dfrac{pnr}{100} = p\left(1 + \dfrac{nr}{100} \right)

2

) In the case of Compound Interest (CI), the amount

A = p \left(1 + \dfrac{r}{100} \right)^{n}

= p\left(1 + \dfrac{r}{100} \right)^{n} - p

3

) Let

p

be the principal or present value of a loan lent at

r \%

interest rate per annum. If

A, B

and

C

are the repayments made at the end of

a, b

and

c

years, wherein the loan is fully repaid, then

p = \dfrac{A}{\left(1 + \dfrac{r}{100} \right)^{a}} + \dfrac{B}{\left(1 + \dfrac{r}{100} \right)^{b}} + \dfrac{C}{\left(1 + \dfrac{r}{100} \right)^{c}}

4

) Where the loan of p, is lent at r %, per time period, for n time periods, and e, is the EMI amount,

p = \dfrac{e}{\left(1 + \dfrac{r}{100} \right)^{1}} + \dfrac{e}{\left(1 + \dfrac{r}{100} \right)^{2}} + ... + \dfrac{e}{\left(1 + \dfrac{r}{100} \right)^{n}}

5) When a certain amount

p

has grown to an amount

A

over

n

years, then Compounded Annual Growth Rate (CAGR) is the variable r in

A = p \left(1 + \dfrac{r}{100} \right)^{n}

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