Simple Interest problems
- 1. If a certain sum is doubled in 8 yr on simple interest, in how many year will it be four times?
Options- A. 24 yr
- B. 16 yr
- C. 32 yr
- D. 12 yr Discuss
Correct Answer: 24 yr
Explanation:
Let the sum be Rs 'y' , so amount = 2y
Simple interest =Rs y
Let R be the rate of interest,
R= (100 x SI)/(P x T) = (100 x y) / (y x 8) = 12.5 %
where SI= Simple Interest
P = Principal
T = Time
now, the needed amount = Rs 4y
since SI = Rs (4x-x)= Rs 3y
since T= (100 x SI)/(P x R)
= (100 x 3y )/(y x 125)= 24 yr
- 2. A sum of money at simple interest amount to Rs 1260 in 2 yr and Rs 1350 in 5 yr, then the rate percent per annum is?
Options- A. 30%
- B. 10%
- C. 2.5%
- D. 5% Discuss
Correct Answer: 2.5%
Explanation:
Simple in 3 year = Rs( 1350 - 1260) = Rs 90
Simple in 2 year = (2/3) &time; 90= Rs 60
Principal = Rs (1260 -60)= Rs 1200
Rate, R= (100 x SI)/(P x T)= (100 x 60)/(1200 x 2)=60/24= 25 %
where , SI= Simple Interest
P= Principal
T= Time
- 3. The difference of 13% per annum and 12% of a sum in 1 year is Rs 110.Then the sum is?
Options- A. Rs 12000
- B. Rs 13000
- C. Rs 11000
- D. Rs 16000 Discuss
Correct Answer: Rs 11000
Explanation:
Let the sum be 'y'
then, [(y x13 x 1)/100 ]- [( y x 12 x 1) / 100]=110
since ( y / 100 ) = Rs 110
? Y = Rs 11000
- 4. At what rate percent per annum simple interest , will a sum of money triple itself in 25 year?
Options- A. 8%
- B. 5%
- C. 6%
- D. 12 % Discuss
Correct Answer: 8%
Explanation:
Let principal amount = P
As amount =3P, T=25 yr
? SI=3P-P=2P
? Rate R = (100 x SI)/(P x T)
where, SI= Simple Interest T = Time
= (100 x 2P)/(P x 25)=8%
- 5. A certain sum at simple interest amounts to Rs 1040 in 3 Yr and to Rs 1360 in 7 yr.Then the sum is?
Options- A. Rs 750
- B. Rs 800
- C. Rs 900
- D. Rs 1000 Discuss
Correct Answer: Rs 800
Explanation:
Simple Interest for 4 yr = Rs(1360 - 1040 ) = Rs 320
so, Simple Interest for 3 yr= Rs [(320/4) x 3]= Rs 240
Sum = Rs (1040-240)= Rs 800
- 6. If the rate of simple interest is 12% per annum the amount that would fetch interest of Rs 6000 per annum is?
Options- A. Rs 7200
- B. Rs 72000
- C. Rs 50000
- D. Rs 48543.69 Discuss
Correct Answer: Rs 50000
Explanation:
Rate of Interest = 12% per annum
Simple Interest =Rs 6000 per annum
Let 'P' is the principal
SI= (P x R x T)/100
where , SI= Simple Interest
T= Time
R= Rate
? 6000=(P x 1 x 12)/100
? P =(6000 x 100)/12
= Rs 50000
Hence the required amount is Rs 50000
- 7. The simple interest on a certain sum for 3 years at 14% per annum is Rs. 235.20. The sum is?
Options- A. Rs. 480
- B. Rs. 560
- C. Rs. 650
- D. Rs. 720 Discuss
Correct Answer: Rs. 560
Explanation:
Required sum = Rs. (100 x SI ) / ( T x R )
= (100 x 235.20) / (3 x 14)
= Rs. 560
- 8. A sum of money amounts to Rs. 702 in 2 years and Rs. 783 in 3 years. The rate percent is?
Options- A. 12% per annum
- B. 13% per annum
- C. 14% per annum
- D. 15% per annum Discuss
Correct Answer: 15% per annum
Explanation:
S.I. for 1 year = Rs. (783 - 702) = Rs 81
S.I. for 2 years = Rs. (81 x 2) = Rs. 162
? Sum = Rs. (702 - 162) = Rs. 540
? Required rate = = (100 x SI) / (P x T) = (100 x 162) / (540 x 2) % = 15%
- 9. If Rs. 64 amount to Rs. 83.20 in 2 years. What will Rs. 86 amount to in 4 years at the same rate percent per annum?
Options- A. Rs. 137.60
- B. Rs. 124.70
- C. Rs. 114.80
- D. Rs. 127.40 Discuss
Correct Answer: Rs. 137.60
Explanation:
S.I on Rs. 64 for 2 year = Rs. 19.20
? Rate = (100 x SI) / (P x T) = (100 x 19.20) / (64 x 2) = 15%
? S.I On Rs. 86 for 4 year = (P x R x T) / 100 = Rs. (86 x 4 x 15 ) /100 = Rs.51.60
? Amount of Rs. 86 after 4 years = Rs. (86 + 51.60) = Rs. 137.60
- 10. A sum of money amounts to Rs. 850 in 3 years and Rs. 925 in 4 year. The sum is?
Options- A. Rs. 600
- B. Rs. 575
- C. Rs. 625
- D. Data inadequate Discuss
Correct Answer: Rs. 625
Explanation:
S.I for 1 year = Rs. (925 - 850) = Rs. 75
S.I for 3 year = Rs. (75 x 3) = Rs. 225
? Sum = Rs. (850 - 225) = Rs. 625
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