**Simple Interest Quantitative Aptitude Study Notes for Bank**

Exam

Exam

You know that quantitative

aptitude section is most important in

good score in bank exam then you have to score good in maths. In competitive

exams the most important thing is time management, if you know how to manage

your time then you can do well in

comes into action. So continuously we are providing shortcut tricks on

different maths topics. Today’s topic is

quantitative aptitude section in bank and SSC exam. You should know how to

in very short time for

From this chapter around 1-2 questions are given in the

time. Interest is the money paid by the

borrower to the lender for the use of money lent. The sum lent is called the

principal. Interest is usually calculated at the rate of so many rupees for

every Rs 100 of the money lent for a year. This is called the rate per cent per

annum.

aptitude section is most important in

**bank**

examsin PO and Clerk and for other competitive exams because if you wantexams

good score in bank exam then you have to score good in maths. In competitive

exams the most important thing is time management, if you know how to manage

your time then you can do well in

**Bank**

Examsas well as in other competitive exams. That’s whereExams

**maths shortcut tricks and formula are**comes into action. So continuously we are providing shortcut tricks on

different maths topics. Today’s topic is

**Simple Interest.**This is the one of the most important topic inquantitative aptitude section in bank and SSC exam. You should know how to

**simple interest****questions and answers**in very short time for

**bank exam.**From this chapter around 1-2 questions are given in the

**SBI and IBPS exams.**For this here we are providing**shortcut tricks**and quicker method to solve**simple interest problems**in very shorttime. Interest is the money paid by the

borrower to the lender for the use of money lent. The sum lent is called the

principal. Interest is usually calculated at the rate of so many rupees for

every Rs 100 of the money lent for a year. This is called the rate per cent per

annum.

‘per annum’ means for a year. The

words ‘per annum’ are sometimes omitted. Thus, 6 p.c. means that Rs 6 is the

interest on Rs 100 in one year.

words ‘per annum’ are sometimes omitted. Thus, 6 p.c. means that Rs 6 is the

interest on Rs 100 in one year.

The sum of the principle and

interest is called the amount.

interest is called the amount.

The interest is usually paid

yearly, half-yearly or quarterly as agreed upon.

yearly, half-yearly or quarterly as agreed upon.

Interest is of two kinds, simple

and compound. When interest is calculated on the original principle for any length

of time it is called simple interest. Compound interest is defined in the next

chapter.

and compound. When interest is calculated on the original principle for any length

of time it is called simple interest. Compound interest is defined in the next

chapter.

To find

multiply the principle by the number of years and by the rate per cent and

divide the result by 100.

**Simple Interest**,multiply the principle by the number of years and by the rate per cent and

divide the result by 100.

This may be remembered in the

symbolic form

symbolic form

**Simple**

Interest formula:

Interest formula:

SI = p*t*r / 100

Where I = interest, p =

principal, t = number of years, r = rate%

principal, t = number of years, r = rate%

**Ex. 1. Find the simple interest on Rs 400 for 5 years at**

6 per cent.

6 per cent.

**Solution:**SI = 400*5*6 / 100

= Rs 120

INTEREST for a number of days

When the time is given in days or

in years and days, 365 days are reckoned to a year. But when the time is given

in months and days, 12 months are reckoned to a year and 30 days to the month. The

day on which the money is paid back should be included but not the day on which

it is borrowed, i.e. in counting, the first day is omitted.

in years and days, 365 days are reckoned to a year. But when the time is given

in months and days, 12 months are reckoned to a year and 30 days to the month. The

day on which the money is paid back should be included but not the day on which

it is borrowed, i.e. in counting, the first day is omitted.

**Ex. 2: Find the simple Interest on Rs 306. 25 from March**

3

at 15/4% per annum.

3

^{rd}to July 27^{th}at 15/4% per annum.

**Solution:**Interest = Rs 306 ¼ * 146/365 * 15/4 * 1/100

Rs 1225/4 * 2/5 * 15/4 * 1/100

= Rs. 147/32

= Rs. 4.59 (nearly)

To Find Principal

Since I = p t r / 100

P = 100 I / t r

**Ex. 3: What sum of money will produce Rs 143 interest in**

3¼ years at 2½ p.c. simple interest?

3¼ years at 2½ p.c. simple interest?

**Solution:**Let the required sum be Rs P. Then

Rs P = Rs 100*143/ 3¼ * 2½

Rs. 100 * 143 * 4 * 2 / 13 * 5

= Rs 1760

To find rate %

Since I = P r t / 100

R = 100 I / P t

**Ex. 4: A sum of Rs 468.75 was lent out at simple interest**

and at the end of 1 year 8 months the total amount was Rs 500. Find the rate of

interest per cent per annum.

and at the end of 1 year 8 months the total amount was Rs 500. Find the rate of

interest per cent per annum.

**Solution:**Here, P = Rs 468.75,

t = 5/3 years

I = Rs (500 – 468.75) = Rs 31.25

Rate p.c. = 100*31.25 /

468.75*5/3 = 100*3125/46875 * 3/5 = 4

468.75*5/3 = 100*3125/46875 * 3/5 = 4

**Ex. 5: A lent Rs 600 to B for 2 years, and Rs 150 to C**

for 4 years and received altogether Rs 90 from both as interest. Find the rate

of interest, simple interest being calculated.

for 4 years and received altogether Rs 90 from both as interest. Find the rate

of interest, simple interest being calculated.

**Solution:**Rs. 600 for 2 years = Rs 1200 for 1 year

And Rs 150 for 4 years = RS 600

for 1 year

for 1 year

Int. = Rs 90

Rate = 90 * 100 / 1800 * 1

= 5%

To Find Time

Since I = P t r / 100

T = 100 I / P r

**Ex. 6: In what time will Rs 8500 amount to Rs 15767.50 at 4½ per cent per**

annum?

annum?

**Solution:**Here, interest = Rs 15767 – Rs 8500 = Rs

7267.50

t = 7267.50*100 / 8500 * 4.5

= 19 years

**Examples**

of Simple Interest with shortcut tricks:

of Simple Interest with shortcut tricks:

**Ex. 7: the simple interest on a sum of money is 1/9**

of the principal, and the number of years is equal to the rate per cent per

annum. Find the rate per cent.

^{th}of the principal, and the number of years is equal to the rate per cent per

annum. Find the rate per cent.

**Solution:**Let Principal = P, time = t years, rate = t

Then, P t t / 100

= P / 9

t

^{2}= 100/9
t = 10/3

or t (rate) = 10/3%

**shortcut trick:**

Rate = time =

= 10/3%

**Ex. 8: A sum of money trebles itself in 20**

yrs at SI. Find the rate of interest.

yrs at SI. Find the rate of interest.

**Solution:**Let the sum be Rs 100.

After 10 years it becomes Rs

200

200

Interest = 200 – 100 = 100

Then, rate = 100 I/ P t

= 100*100 / 100*10 = 10%

**Shortcut trick:**time * rate = 100 (Multiple

number of principal – 1)

Or, rate = 100 * multiple

number of principle – 1 / time

number of principle – 1 / time

Using the above formula: rate =

100 (2-1) / 10

100 (2-1) / 10

= 10%

**Ex. 9: A sum was put at SI at a certain**

rate for 2 yrs. Had it been put at 3 % higher rate, it would have fetched Rs

300 more. Find the sum.

rate for 2 yrs. Had it been put at 3 % higher rate, it would have fetched Rs

300 more. Find the sum.

**Solution:**Let the sum be Rs x and the

original rate be y % per annum. Then, new rate = (y + 3) % per annum.

X(y + 3) * 2 / 100 – x(y)*2 /

100 = 300

100 = 300

xy + 3x – xy = 15000 or x =

5000

5000

thus, the sum = Rs. 5000

**shortcut trick:**sum = more interest*100 /

time*more rate

= 300*100 / 2*3

= 500

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