Simple Interest - Quantitative Aptitude (MCQ) questions

1)   Find the principal which yields a simple interest of Rs. 20 and compound interest of Rs. 21 in two years, at the same percent rate per annum?
- Published on 06 May 16

a. Rs. 520
b. Rs. 480
c. Rs. 420
d. Rs. 200
Answer  Explanation 

ANSWER: Rs. 200

Explanation:
SI in 2 years = Rs. 20, SI in 1 year = Rs. 10
CI in 2 years = Rs. 21
% rate per annum = [(CI – SI) / (SI in 1 year)] *100
= [(21 – 20) / 20] * 100
= 5 % p.a.

Let the principal be Rs. X
Time = T = 2 years
% rate = 5% p.a.
SI = (PRT/100)
20 = (X*5*2) / 100
X = Rs. 200


2)   A sum of Rs. 4000 amounts to Rs. 4600 in 5 years at a certain rate of simple interest. What would be the amount, if the rate of interest is increased by 3 %.
- Published on 25 Apr 16

a. Rs. 4900
b. Rs. 5000
c. Rs. 5200
d. Rs. 5600
e. None of these
Answer  Explanation 

ANSWER: Rs. 5200

Explanation:
Principal = Rs. 4000, Amount = Principal + SI = Rs. 4600
SI = Amount – Principal = 4600 – 4000 = Rs. 600
Given : Principal = Rs. 4000, Time = T = 5 years and SI = Rs. 600
SI =PRT/100
600 = 4000 *R * 5/100
600 = 200R
R = 3 % p.a.
Now the new interest rate is = 3% + 3% = 6 % p.a.
SI = PRT/ 100 = 4000 * 6 * 5/ 100 = Rs. 1200
Amount = Principal + SI
= 4000 + 1200
= 5200


3)   Akhil borrowed a certain sum of money at the rate of 6%, 9% and 14% for a period of first two years, next three years and beyond the period of five years respectively. If at the end of nine years, he paid Rs. 8550 as interest, then find the sum of money he had borrowed.
- Published on 20 Apr 16

a. Rs. 9,000
b. Rs.14,000
c. Rs.15,000
d. Rs.18,000
e. None of these
Answer  Explanation 

ANSWER: Rs. 9,000

Explanation:
Let Rs.P be the money borrowed by Akhil.
I) R = 6%, T = 2 years
Simple Interest of 2 years = PRT/100
= P * 6 * 2/100 = 12P/100
II) R = 9%, T = 3 years
Simple Interest of 3 years = P * 9 * 3/100 = 27P/100
III) R = 14%, T = 4 years
Simple Interest of 3 years= P * 14 * 4/100 = 56P/100
Therefore, total Simple Interest of 9 years
= 12P/100 + 27P/100 + 56P/100
= 95P/100
The total interest paid after nine years = Rs.8550
95P/100 = 8550
Therefore, 95P = 855,000
P = 855,000/95 = Rs. 9,000
Amount of money borrowed by Akhil = Rs. 9,000


4)   Mr. Karan borrowed a certain amount at 6% per annum simple interest for 9 years. After 9 years, he returned Rs. 8110/-. Find out the amount that he borrowed.
- Published on 19 Apr 16

a. Rs. 4,900
b. Rs. 5,000
c. Rs. 5,100
d. Rs. 5266
e. None of these
Answer  Explanation 

ANSWER: Rs. 5266

Explanation:
Let us assume Mr. Karan borrowed amount is Rs. A. (the principal)
By formula of simple interest, S.I. = PRT / 100
Where P = The principal, R = Rate of interest as a %, T = Time in years
S.I. = (P * 6 * 9)/100 = 54 P/100
Amount = Principal + S.I.
8110 = P + (54P/100)
8110 = (100P + 54P)/100
8110 = 154P/100
P = (8110 * 100)/154 = Rs. 5266.233


5)   In how many years, Rs. 200 will produce the same interest @ 5 % as Rs. 900 produce in 2 years @ 3 ½ %?
- Published on 06 Apr 16

a. 6.3 years
b. 8.2 years
c. 9 years
d. 12 years
Answer  Explanation 

ANSWER: 6.3 years

Explanation:
P = Rs 900, R = 3 ½ % = 7/2 %, T = 2 years.
Therefore,
S.I. = PRT/100
S.I. = Rs. (900 x 7/2 x 2/100) = Rs. 63
Now, P = Rs. 200, S.I. = Rs. 63, R = 5 %
Time = ((100 x 63) / (200 x 5) ) years = 6.3 years


6)   A certain sum earns simple interest of Rs. 800 in 2 years at a certain rate of interest. If the same sum earns compound interest of Rs. 845 in the same period of 2 years, What must be the rate of interest?
- Published on 05 Apr 16

a. 5% p.a.
b. 7.5% p.a.
c. 10% p.a.
d. 12.5% p.a.
Answer  Explanation 

ANSWER: 10% p.a.

Explanation:
Given: 800 = (P * R * 2) / 100
S.I. For 1 year = Rs. 400
Thus, (840 – 800) = S.I. on Rs. 400 for 1 year
40 = (400 * R * 1) / 100
R = 10% p.a.


7)   Find the simple interest on Rs. 78000 at 15(2/5) % per annum for 9 months.
- Published on 25 Mar 16

a. Rs. 7804
b. Rs. 8979
c. Rs. 8046
d. Rs. 9009
Answer  Explanation 

ANSWER: Rs. 9009

Explanation:
P = Rs. 78000, R = 77/5 % p.a and T = 9/12 years = ¾ years
Therefore,
S.I = (P*R*T)/100
= (78000* 77/5 * ¾ * 1/100)
= Rs. 9009


8)   Simple interest at x% for x years will come out to be Rs x on a sum of Rs?
- Published on 15 Jun 15

a. x
b. 100/x
c. 100/x2
d. 100x
Answer  Explanation 

ANSWER: 100/x

Explanation:
Formula for Simple Interest:

SI = Principal*Rate*Time

SI= x

Rate= x/100

Time= x

=> x= Principal*(x/100)*x

=>Principal Amount= 100/x


9)   What is the minimum number of years upon which SI on Rs 2600 at 6.67% interest rate will be in whole number?
- Published on 15 Jun 15

a. 2
b. 6
c. 3
d. 4
Answer  Explanation 

ANSWER: 3

Explanation:
Simple Interest =Principal * Rate * Time

Principal = 2600 Rs

Interest Rate = 6.67%

=> SI = 2600 * (20/3)*Time

SI of the number will be a whole number for the first time when time is three as denominator of rate is 3.

Hence time should be set to 3 years.


10)   What time will be taken by an amount of Rs. 900 to yield Rs. 81 as interest at 4.5% per annum of simple interest?
- Published on 19 Oct 15

a. 2 years
b. 1 years
c. 3 years
d. 4 years
Answer  Explanation 

ANSWER: 2 years

Explanation:
P= Rs 900

Rate = 4.5*

SI= Rs 81

=> SI= Time*P*rate

calculating for rate,

=> Time= SI/rate*P

= 81/4.5%*900

=> 2 years

Thus, it will take 2 years to yield Rs 81.


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