A certain principal amount, invested at simple interest, grows to Tk. 950 after 3 years and Tk. 1010 after 4 years. What is the original principal amount?
A
Tk. 800
B
Tk. 720
C
Tk. 650
D
Tk. 770
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Question: A certain principal amount, invested at simple interest, grows to Tk. 950 after 3 years and Tk. 1010 after 4 years. What is the original principal amount?
Solution:
Given,
Amount after 3 years = Tk. 950
Amount after 4 years = Tk. 1010
∴ Interest for 1 year = 1010 - 950 = Tk. 60
∴ Interest for 3 years = 60 × 3 = Tk. 180
∴ Principal = 950 - 180 = Tk. 770
0
Updated: 1 month ago
How many years will Tk. 1500 need at 4% simple interest to earn the same interest as Tk. 2000 earns in 3 years at 5% simple interest?
Created: 3 months ago
A
4 years
B
5 years
C
6 years
D
8 years
Solution:
Interest from Tk. 2000 in 3 years at 5%:
SI = (P × R × T)/100
= (2000 × 5 × 3)/100
= 300 Tk.
Now,
Tk. 1500 to Produce the Same Interest (Tk. 300) at 4%:
Principal, P = Tk. 1500
Interest, SI = Tk. 300
Interest Rate, R = 4%
Time, T = ? years
SI = PRT/100
⇒ T = (SI × 100)/(P × R)
⇒ T = (300 × 100)/(1500 × 4)
⇒ T = 30000/6000
∴ T = 5 years
0
Updated: 3 months ago
A sum of Tk. 30,000 yields a compound interest of Tk. 4347 when invested at 7% per annum. What is the investment period in years?
Created: 3 months ago
A
2 years
B
4 years
C
3 years
D
5 years
Solution:
Given,
Principal, P = 30000
Rate, r = 7% per annum
Compound Interest, CI = 4347
We know,
Amount, A = P + CI = 30000 + 4347 = 34347
Using the compound amount formula:
A = P(1 + r/100)n
⇒ 34347 = 30000 × (1 + 7/100)n
⇒ 34347 = 30000 × (107/100)n
⇒ (107/100)n = 34347/30000
⇒ (1.07)n = 1.1449
⇒ (1.07)n = (1.07)2
∴ n = 2 years
0
Updated: 3 months ago
The simple interest on a certain sum at 6% p.a. is Tk. 360 in 1 year. What will be the additional interest earned in 1 year if the rate increases to 7% p.a. on the same sum?
Created: 3 months ago
A
Tk. 60
B
Tk. 80
C
Tk. 70
D
Tk. 100
Solution:
Given,
Interest at 6% for 1 year:
Simple Interest, SI1 = Tk. 360
Interest rate, R = 6%
Time, T = 1 year (initial)
We know,
SI1 = PRT/100
⇒ 360 = (P × 6 × 1)/100
⇒ P = (360 × 100)/6
∴ P = Tk. 6000
So, the original sum (principal) is Tk. 6000.
Now,
Interest at 7% for 1 year:
SI2 = PRT/100
⇒ SI2 = (6000 × 7 × 1)/100
⇒ SI2 = Tk. 420
Additional interest = SI2 - SII
= 420 - 360
= Tk. 60
0
Updated: 3 months ago
