# Quant Questions – Simple Interest & Compound Interest Set-6

Dear Readers, Important Practice Aptitude Questions for SBI Clerk& IBPS Exams was given here with Solutions. Aspirants those who are preparing for the Bank Examination and other Competitive Examination can use this material.

1. A sum of money becomes four times in 20 years at simple interest. Find the rate of interest.

1. 15%
2. 12%
3. 18%
4. 9%
5. None of these
1). Let the sum be ‘P’
Then, the sum after 20 years is ‘4P’
∴ Simple interest = 4P – P = 3P
Formula for S.I = (PRT / 100)
∴ 3P= (P × R × 20) / 100
R = (3P × 100) / (20 × P) = 15 %

2. In 4 year, Rs. 6000 amounts to Rs. 8000. In what time at the same rate, will Rs. 525 amounts to Rs. 700?

1. 2 years
2. 3 years
3. 4 years
4. 5 years
5. None of these
2).Amount (A) = 8000; T = 4 yrs; Principal (P) = 6000
S.I = A – P = 8000 – 6000 =2000; R =?
Formula for S.I = (PRT / 100)
2000 = (6000 × R × 4) / 100
∴ R = 25/3 %
Now, we calculate T , for A = 700; P= 525;
S.I = A – P = 700 – 525 = 175
S.I = (525 × 25 / 3 × T) / 100
175 = (525 × 25 × T) / (100 × T)
Hence, T = 4 years

3. Swathi borrowed some money at the rate of 6% per annum for the first three years, at the rate of 9% per annum for the next five years and at the rate of 13% per annum for the period beyond eight years. If she pays a total interest of Rs.8160 at the end of eleven years, how much money did she borrow?

1. Rs.8000
2. Rs.12000
3. Rs.10000
5. None of these
3). Let the sum borrowed is P,
Then, according to the question [(P × 6 × 3) / 100] + [(P × 9 × 5) / 100] + [(P × 13 × 3) / 100] = 8160
(18P + 45P + 39P)/100 = 8160
102P / 100 = 8160
∴ P = 8000
Hence, Swathi borrowed Rs. 8000

4. If a certain sum at compound interest becomes double in 5 year, then in how many years, it will be 16 times at the same rate of interest?

1. 10 years
2. 15 years
3. 20 years
4. Cannot be determined
5. None of these
4). Let Sum be X,
X becomes 2X in 5 years
2X becomes 4X in 10 years
4X becomes 8X in 15 years
Hence, 8X becomes 16X in 20 years

5. At simple interest, a sum becomes three times in 20 years. Find the time in which the sum will be double at the same rate of interest?

1. 8 years
2. 10 years
3. 12 years
4. 14 years
5. None of these
5). Let Sum = P, T= 20 yrs;
∴ S.I = 3P – P = 2P
Formula for S.I = (PRT) / 100
2P = (P × R × 20) / 100
R = 10%
To find Time (T),
∴ S.I = 2P – P = P
P = (P × 10 × T) / 100
Hence, T = 10 yrs.

6. If the difference between the simple interest and compound interest on some amount at 20% pa for 3 years is 48, then what must be the principal amount?

1. Rs. 240
2. Rs. 375
3. Rs. 480
4. Rs. 180
5. None of these
6). Formula for calculating, difference between C.I and S.I for 3 years is,
P = D × 1003 / R2 (300 + R)
P= 48 × 1003 / 202 (300+20)
P = (48×100×100×100) / [400 (320)] P= 375

7. A sum of money invested at compound interest amounts to Rs. 800 in 3 years and Rs.882 in 5 years. What is the rate of interest?

1.  2.5%
2.  4%
3.  5%
4.  6.6%
5. None of these
7). Formula for calculating Amount (A) in C.I
A= P (1+R/100)T
Hence, P [1 + (R/100)]3 = 800 …..(1)
P [1 + (R/100)]5 = 882 ….(2)
Since, (2)/(1) = P [1 + (R/100)]5 / P [1 + (R/100)]3 = 882/800
[1 + (R/100)]2 = 441/400
[1 + (R/100)] = √(441 / 400) = 21 / 20
∴ R = (1/20) × 100 = 5%

8. Simple interest for the sum of Rs.1500 is Rs.50 in 4 years and Rs.80 in 8 years. Find the rate of SI?

1. 0.5%
2. 1%
3. 1.5%
4. 2%
5. None of these
8). S.I = (PRT / 100)
According to the question, = [(1500 × R × 8) / 100] – [(1500 × R × 4) / 100] = 80 – 50 (12000R – 6000R) / 100 = 30
6000R / 100 = 30
R = 30/60 = ½ = 0.5%

9. Simple interest on an amount after 24 months at the rate of 2% per quarter is 960. What is the amount?

1. 2000
2. 5200
3. 6000
4. 4800
5. None of these
9). S.I = (PRT) / 100
Hence, P = (S.I × 100) / (R×T)
P = (960 × 100) / (8×2) = 6000

10. At what rate percent per annum will a sum of money double in 8 years?

1. 10%
2. 14%
3. 12.5%
4. Cannot be determined
5. None of these
10). Let P= X, S.I =X, T =8 yrs, R=?
R = (S.I × 100) / (P×T) = (x ×100) / (x × 8) = 12.5% 