Simple Interest Questions -02

This post is a collection of important simple interest questions which has been asked in competition exams like GMAT, CAT, NMAT, CMAT and government entrance examinations like SSC, SSC-CGL, Banking, SBI PO, SBI clerk, NABARD, IBPS, LIC AAO etc.

For your convenience, all the questions are provided with detailed solutions. I request you to practice each of them and try to understand the concept behind each questions

Solved Simple Interest Problems

(01) The sum of money that will give Re. 1 as interest per day at the rate of 5% per annum, the simple interest is?

Interest per day = Re. 1
Annual Interest = 1 * 365 = Rs. 365
Rate of Interest = 5%

Find the required Principal

P => 365 × 100 / 5 = Rs. 7300
Hence rs. 7300 will give interest of 1 Re. per day at the rate of 5% per annum

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(02) Mohan lent some amount of money at 9% simple interest and an equal amount of money at 10% simple interest each for two years. If his total interest was Rs. 760, what amount was lent in each case?

Let
P1 =x
R1= 9%
T1 = 2 years

And
P2=x
R2 =10%
T2= 2 years

According to the question, the total interest received after two years is Rs 760

18x + 20x = 76000

x = 76000 / 38 = 2000

Hence Rs. 2000 was lent to each person

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(03) If the simple interest on a certain sum of money for 15 months at 7.5% per annum exceeds the simple interest on the same sum for 8 months at 12.5% per annum by Rs 32.5, then the sum of money (in Rs.) is:

P1 = x
R1= 15/2 %
T1 = 15 months

Also,
P2= x
R2= 25/2 %
T2 = 8 Months

According to question

225x – 200x = 78000

x = 78000 / 25 = Rs. 3,120

Hence the initial principal is rs 3,120

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(04) The Simple Interest on Rs. 7,300 from 11 May, 1987 to 10 September, 1987 (both days included), at 5% per annum is

Time from 11 May to 10 Sep, 1987 = 21 + 30 + 31 + 31 + 10 = 123 days

Time = 123 / 365 year

Hence we will get 123 Rs interest in the above duration

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(05) A person borrows Rs. 5000 for 2 years at 4% per annum simple interest. He immediately lends it to another person at 25/4 % per annum simple interest for 2 years. His gain in this transaction is ?

P1 = Rs 5000
R1=4%
T1= 2 years

P2 = Rs 5000
R2= 25/4%
T2 = 2 years

First Case Simple interest

Second Case Simple Interest

Gain in the transaction = Rs. (625 – 400) = Rs. 225

Hence the person gains rs 225 in the above transaction

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(06). A certain sum of money becomes three times of itself in 20 years at simple interest. In how many years, does it become double of itself in the same rate of interest?

Money becomes three times in 30 years

Let Principal = P,
then amount = 3P,
SI = 3P – P = 2P

After calculation we get R = 10%

Now we have to find the time at which money gets double at 10% rate
Amount = 2P
SI = 2P – P =P

After calculation we get time T = 10 years

Hence in 10 years the money will double

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P1= x
R1 =10%
T1 = 5 years

and,
P2 = 1500-x
R2= 12.5%
T2= 4 years

According to question

50x = 75000 – 50x

x = 75000 / 100 = 750

Sum lent out at 12.5% = 1500 – 750 = Rs. 750

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Let the amount invested in all three schemes be x, y and z.

P1= x
R1 =10%
T1 = 6 years

and,
P2 = y
R2= 12%
T2= 10 years

and,
P3 = z
R3= 15%
T3= 12 years

According to question:

60x = 120y = 180z

x = 2y = 3z

x = k, y = k/2 and z = k/3

x : y : z = k : k/2 : k/3 = 6 : 3 : 2

Hence the ratio of investment is 6:3:2

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P + SI for 5 years = 5200 — eq(1)
P + SI for 7 years = 5680 — eq(2)

Subtracting eq (2) with eq(1) we get
SI for 2 years = 480
Thus, SI for one year = 240

Putting SI value in eq(1)
P + 5 × 240 = 5200
P = Rs. 4000

Hence the rate of simple interest is 6%

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(10) Simple Interest on Rs. 500 for 4 years at 6.25% per annum is equal to the simple interest on Rs. 400 at 5% per annum for a certain period of time. The period of time is?

P1= Rs 500
R1= 6.25%
T1= 4 years

And,
P2= Rs. 400
R2= 5%
T2= ?

According to question

Hence 6.25 years is the required time