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All questions of Simple & Compound Interest for JAMB Exam
The simple interest on a sum of money is ₦450 at a rate of 5% per annum. How long will it take for the principal to double?- a)20 years
- b)15 years
- c)6 years
- d)10 years
Correct answer is option 'A'. Can you explain this answer?
The simple interest on a sum of money is ₦450 at a rate of 5% per annum. How long will it take for the principal to double?
a)
20 years
b)
15 years
c)
6 years
d)
10 years
|
Sun Ray Institute answered |
The formula for simple interest is:
SI = (P × R × T) / 100
Where:
- SI = Simple Interest
- P = Principal
- R = Rate of interest per annum
- T = Time in years
Step 1: When the principal doubles
If the principal doubles, then SI = P. Substituting into the formula:
P = (P × R × T) / 100
Canceling out P:
1 = (R × T) / 100
Solve for T:
T = 100 / R
Step 2: Substitute the given rate
The rate of interest, R = 5%:
T = 100 / 5 = 20 years
Final Answer:
The principal will double in 20 years
If ₦3,500 is invested at a simple interest rate of 6% per annum, how much interest will be earned after 4 years?- a)₦1200
- b)₦1,260
- c)₦840
- d)₦2,100
Correct answer is option 'C'. Can you explain this answer?
If ₦3,500 is invested at a simple interest rate of 6% per annum, how much interest will be earned after 4 years?
a)
₦1200
b)
₦1,260
c)
₦840
d)
₦2,100
|
|
Sun Ray Institute answered |
- Write Down the Simple Interest Formula: I = (P × R × T) / 100
- Plug in the Given Values: I = (₦3,500 × 6 × 4) / 100
- Perform the Calculations Step-by-Step:
- Multiply Principal by Rate: 3,500 × 6 = 21,000
- Multiply the Result by Time: 21,000 × 4 = 84,000
- Divide by 100 to Find the Interest: 84,000 / 100 = 840
- Multiply Principal by Rate:
- Final Calculation: I = ₦840
If the simple interest on a principal of ₦12,000 for 3 years is ₦3,240, what is the annual interest rate?- a)7%
- b)8%
- c)9%
- d)10%
Correct answer is option 'C'. Can you explain this answer?
If the simple interest on a principal of ₦12,000 for 3 years is ₦3,240, what is the annual interest rate?
a)
7%
b)
8%
c)
9%
d)
10%
|
|
Sun Ray Institute answered |
Interest = Principal × Rate × Time, where Interest = ₦3,240, Principal = ₦12,000, and Time = 3 years. Rearranging the formula:
Rate = (Interest / (Principal × Time)) × 100
= (₦3,240 / (₦12,000 × 3)) × 100
= 9%.
Rate = (Interest / (Principal × Time)) × 100
= (₦3,240 / (₦12,000 × 3)) × 100
= 9%.
If Rs.5,000 is invested at a simple interest rate of 7% per annum, how long will it take for the interest to amount to Rs.1,400?- a)2 years
- b)4 years
- c)3 years
- d)5 years
Correct answer is option 'B'. Can you explain this answer?
If Rs.5,000 is invested at a simple interest rate of 7% per annum, how long will it take for the interest to amount to Rs.1,400?
a)
2 years
b)
4 years
c)
3 years
d)
5 years
|
|
Sun Ray Institute answered |
The formula for calculating simple interest is:
I = (P × R × T) / 100
Where:
Where:
- I = Interest (₦1,400)
- P = Principal (₦5,000)
- R = Rate of interest (7%)
- T = Time (in years, to be calculated)
Substitute the given values:
Rs 1,400 = (Rs5,000 × 7 × T) / 100
Simplify:
1,400 = (35,000 × T) / 100
1,400 = 350T
Solve for T:
T = 1,400 / 350 = 4 years
Correct Answer:
b) 4 years
The simple interest on a sum of money at 5% per annum for 2 years is N800. What is the principal amount?- a)N4,000
- b)N5,000
- c)N6,000
- d)N8,000
Correct answer is option 'B'. Can you explain this answer?
The simple interest on a sum of money at 5% per annum for 2 years is N800. What is the principal amount?
a)
N4,000
b)
N5,000
c)
N6,000
d)
N8,000
|
|
Sun Ray Institute answered |
Simple interest can be calculated using the formula:
Simple Interest = (Principal × Rate × Time) / 100.
Substituting the values: (Principal × 5 × 2) / 100
= 800.
Solving for Principal gives Principal = (800 × 100) / (5 × 2)
= N5,000.
Simple Interest = (Principal × Rate × Time) / 100.
Substituting the values: (Principal × 5 × 2) / 100
= 800.
Solving for Principal gives Principal = (800 × 100) / (5 × 2)
= N5,000.
A sum of N12,000 is invested at a compound interest rate of 8% per annum, compounded semi-annually. What will be the amount at the end of 2 years?- a)N14,760
- b)N14,800
- c)N14,820
- d)N14,880
Correct answer is option 'D'. Can you explain this answer?
A sum of N12,000 is invested at a compound interest rate of 8% per annum, compounded semi-annually. What will be the amount at the end of 2 years?
a)
N14,760
b)
N14,800
c)
N14,820
d)
N14,880
|
|
Sun Ray Institute answered |
Compound interest can be calculated using the formula:
Amount = Principal × (1 + Rate/100)(Time × Frequency).
Here, the frequency is semi-annually,
so Time × Frequency = 2 × 2 = 4.
Substituting the values: 12,000 × (1 + 8/100)4
= N14,880.
Amount = Principal × (1 + Rate/100)(Time × Frequency).
Here, the frequency is semi-annually,
so Time × Frequency = 2 × 2 = 4.
Substituting the values: 12,000 × (1 + 8/100)4
= N14,880.
If an amount doubles itself in 10 years at a certain rate of interest, what is the rate of interest?- a)6%
- b)7%
- c)8%
- d)10%
Correct answer is option 'C'. Can you explain this answer?
If an amount doubles itself in 10 years at a certain rate of interest, what is the rate of interest?
a)
6%
b)
7%
c)
8%
d)
10%
|
|
Sun Ray Institute answered |
The rate of interest can be calculated using the formula:
Rate = (100 × Simple Interest) / (Principal × Time).
Since the amount doubles itself in 10 years, the simple interest is equal to the principal amount.
Therefore, Rate = (100 × 100) / (100 × 10)
= 8%.
Rate = (100 × Simple Interest) / (Principal × Time).
Since the amount doubles itself in 10 years, the simple interest is equal to the principal amount.
Therefore, Rate = (100 × 100) / (100 × 10)
= 8%.
If a sum of N6,000 amounts to N7,500 in 2 years at a certain rate of interest, what is the rate of interest?- a)8%
- b)10%
- c)12%
- d)15%
Correct answer is option 'C'. Can you explain this answer?
If a sum of N6,000 amounts to N7,500 in 2 years at a certain rate of interest, what is the rate of interest?
a)
8%
b)
10%
c)
12%
d)
15%
|
|
Sun Ray Institute answered |
The rate of interest can be calculated using the formula:
Rate = [(Amount - Principal) / Principal] × (100 / Time).
Substituting the values: [(7,500 - 6,000) / 6,000] × (100 / 2)
= 12%.
Rate = [(Amount - Principal) / Principal] × (100 / Time).
Substituting the values: [(7,500 - 6,000) / 6,000] × (100 / 2)
= 12%.
If the simple interest on a principal of ₦8,000 for 2 years is ₦1,280, what is the annual interest rate?- a)7%
- b)8%
- c)9%
- d)10%
Correct answer is option 'D'. Can you explain this answer?
If the simple interest on a principal of ₦8,000 for 2 years is ₦1,280, what is the annual interest rate?
a)
7%
b)
8%
c)
9%
d)
10%
|
|
Sun Ray Institute answered |
Interest = Principal × Rate × Time, where Interest = ₦1,280, Principal = ₦8,000, and Time = 2 years. Rearranging the formula:
Rate = (Interest / (Principal × Time)) × 100
= (₦1,280 / (₦8,000 × 2)) × 100
= 10%.
Rate = (Interest / (Principal × Time)) × 100
= (₦1,280 / (₦8,000 × 2)) × 100
= 10%.
The compound interest on a sum of N10,000 at 6% per annum for 2 years, compounded annually, is N________.- a)N1,150.60
- b)N1,195.20
- c)N1,200
- d)N1,212.20
Correct answer is option 'B'. Can you explain this answer?
The compound interest on a sum of N10,000 at 6% per annum for 2 years, compounded annually, is N________.
a)
N1,150.60
b)
N1,195.20
c)
N1,200
d)
N1,212.20
|
|
Sun Ray Institute answered |
Compound interest can be calculated using the formula:
Compound Interest = Principal × [(1 + Rate/100)Time - 1].
Substituting the values: 10,000 × [(1 + 6/100)2 - 1]
= N1,195.20.
Compound Interest = Principal × [(1 + Rate/100)Time - 1].
Substituting the values: 10,000 × [(1 + 6/100)2 - 1]
= N1,195.20.
A woman borrowed ₦10,000 at a simple interest rate of 8% per annum. If she repays the loan after 3 years, how much interest will she have to pay?- a)₦1,800
- b)₦2,400
- c)₦2,800
- d)₦3,200
Correct answer is option 'B'. Can you explain this answer?
A woman borrowed ₦10,000 at a simple interest rate of 8% per annum. If she repays the loan after 3 years, how much interest will she have to pay?
a)
₦1,800
b)
₦2,400
c)
₦2,800
d)
₦3,200
|
|
Sun Ray Institute answered |
Interest = Principal × Rate × Time
= ₦10,000 × 0.08 × 3
= ₦2,400.
= ₦10,000 × 0.08 × 3
= ₦2,400.
If an amount of N50,000 is invested at an interest rate of 8% per annum for 3 years, what will be the simple interest earned?- a)N12,000
- b)N12,800
- c)N16,000
- d)N16,800
Correct answer is option 'B'. Can you explain this answer?
If an amount of N50,000 is invested at an interest rate of 8% per annum for 3 years, what will be the simple interest earned?
a)
N12,000
b)
N12,800
c)
N16,000
d)
N16,800
|
|
Sun Ray Institute answered |
Simple interest can be calculated using the formula:
Simple Interest = (Principal × Rate × Time) / 100.
Substituting the values: (50,000 × 8 × 3) / 100
= N12,000.
Simple Interest = (Principal × Rate × Time) / 100.
Substituting the values: (50,000 × 8 × 3) / 100
= N12,000.
A sum of ₦10,000 is invested in a bank at an annual interest rate of 5%. How much interest will be earned after 2 years?- a)₦500
- b)₦1,000
- c)₦1,500
- d)₦2,000
Correct answer is option 'B'. Can you explain this answer?
A sum of ₦10,000 is invested in a bank at an annual interest rate of 5%. How much interest will be earned after 2 years?
a)
₦500
b)
₦1,000
c)
₦1,500
d)
₦2,000
|
|
Sun Ray Institute answered |
Interest = Principal × Rate × Time
= ₦10,000 × 0.05 × 2
= ₦1,000.
= ₦10,000 × 0.05 × 2
= ₦1,000.
A sum of N10,000 is invested at a compound interest rate of 6% per annum for 2 years. What will be the compound interest earned at the end of the period?- a)N1,200
- b)N1,220.80
- c)N1,260
- d)N1,262.40
Correct answer is option 'B'. Can you explain this answer?
A sum of N10,000 is invested at a compound interest rate of 6% per annum for 2 years. What will be the compound interest earned at the end of the period?
a)
N1,200
b)
N1,220.80
c)
N1,260
d)
N1,262.40
|
|
Sun Ray Institute answered |
Compound interest can be calculated using the formula:
Compound Interest = Principal × [(1 + Rate/100)Time - 1].
Substituting the values: 10,000 × [(1 + 6/100)2 - 1]
= N1,220.80.
Compound Interest = Principal × [(1 + Rate/100)Time - 1].
Substituting the values: 10,000 × [(1 + 6/100)2 - 1]
= N1,220.80.
A man borrowed ₦20,000 at a simple interest rate of 10% per annum. If he repays the loan after 2 years, how much interest will he have to pay?- a)₦2,000
- b)₦4,000
- c)₦3,000
- d)₦5,000
Correct answer is option 'B'. Can you explain this answer?
A man borrowed ₦20,000 at a simple interest rate of 10% per annum. If he repays the loan after 2 years, how much interest will he have to pay?
a)
₦2,000
b)
₦4,000
c)
₦3,000
d)
₦5,000
|
|
Sun Ray Institute answered |
Interest = Principal × Rate × Time
= ₦20,000 × 0.10 × 2
= ₦4,000.
= ₦20,000 × 0.10 × 2
= ₦4,000.
A sum of ₦7,500 is invested in a bank at an annual interest rate of 4%. How much interest will be earned after 3 years?- a)₦800
- b)₦1,200
- c)₦900
- d)₦1,800
Correct answer is option 'C'. Can you explain this answer?
A sum of ₦7,500 is invested in a bank at an annual interest rate of 4%. How much interest will be earned after 3 years?
a)
₦800
b)
₦1,200
c)
₦900
d)
₦1,800
|
|
Sun Ray Institute answered |
Interest = Principal × Rate × Time
= ₦7,500 × 0.04 × 3
= ₦900.
= ₦7,500 × 0.04 × 3
= ₦900.
A sum of ₦5,000 is invested at a simple interest rate of 8% per annum. How long will it take for the interest to amount to ₦1,200?- a)2 years
- b)3 years
- c)4 years
- d)5 years
Correct answer is option 'D'. Can you explain this answer?
A sum of ₦5,000 is invested at a simple interest rate of 8% per annum. How long will it take for the interest to amount to ₦1,200?
a)
2 years
b)
3 years
c)
4 years
d)
5 years
|
|
Sun Ray Institute answered |
Interest = Principal × Rate × Time, where Principal = ₦5,000, Interest = ₦1,200, and Rate = 8% per annum. Rearranging the formula:
Time = Interest / (Principal × Rate)
= ₦1,200 / (₦5,000 × 0.08)
= 5 years.
Time = Interest / (Principal × Rate)
= ₦1,200 / (₦5,000 × 0.08)
= 5 years.
A sum of N20,000 is invested at a compound interest rate of 7% per annum, compounded annually. How many years will it take for the amount to double?- a)8 years
- b)10 years
- c)12 years
- d)14 years
Correct answer is option 'B'. Can you explain this answer?
A sum of N20,000 is invested at a compound interest rate of 7% per annum, compounded annually. How many years will it take for the amount to double?
a)
8 years
b)
10 years
c)
12 years
d)
14 years
|
|
Sun Ray Institute answered |
The solution involves determining how long it will take for an investment to double at a compound interest rate of 7% per annum.
- We use the compound interest formula: A = P(1 + r)^n, where:
- A is the future amount.
- P is the principal amount (N20,000).
- r is the annual interest rate (0.07).
- n is the number of years.
- To double the investment, A should be twice P, i.e., A = 2P.
- Substitute into the formula: 2P = P(1 + 0.07)^n.
- Cancel P from both sides: 2 = (1.07)^n.
- We solve for n using logarithms: n = log(2) / log(1.07).
- Calculating gives n ≈ 10.24.
- Thus, it will take approximately 10 years for the amount to double.
Therefore, the correct answer is B: 10 years.
A principal amount of N8,000 is invested at an annual interest rate of 5%. How much interest will be earned at the end of 4 years?- a)N1,400
- b)N1,600
- c)N1,800
- d)N2,000
Correct answer is option 'B'. Can you explain this answer?
A principal amount of N8,000 is invested at an annual interest rate of 5%. How much interest will be earned at the end of 4 years?
a)
N1,400
b)
N1,600
c)
N1,800
d)
N2,000
|
|
Sun Ray Institute answered |
Simple interest can be calculated using the formula:
Simple Interest = (Principal × Rate × Time) / 100.
Substituting the values: (8,000 × 5 × 4) / 100
= N1,600.
Simple Interest = (Principal × Rate × Time) / 100.
Substituting the values: (8,000 × 5 × 4) / 100
= N1,600.
A sum of N5,000 is invested at a compound interest rate of 10% per annum, compounded annually. What will be the amount at the end of 3 years?- a)N5,500
- b)N6,105
- c)N6,600
- d)N6,805
Correct answer is option 'C'. Can you explain this answer?
A sum of N5,000 is invested at a compound interest rate of 10% per annum, compounded annually. What will be the amount at the end of 3 years?
a)
N5,500
b)
N6,105
c)
N6,600
d)
N6,805
|
|
Sun Ray Institute answered |
Compound interest can be calculated using the formula:
Amount = Principal × (1 + Rate/100)Time.
Substituting the values: 5,000 × (1 + 10/100)3
= N6,600.
Amount = Principal × (1 + Rate/100)Time.
Substituting the values: 5,000 × (1 + 10/100)3
= N6,600.
Chapter doubts & questions for Simple & Compound Interest - Mathematics for JAMB 2025 is part of JAMB exam preparation. The chapters have been prepared according to the JAMB exam syllabus. The Chapter doubts & questions, notes, tests & MCQs are made for JAMB 2025 Exam. Find important definitions, questions, notes, meanings, examples, exercises, MCQs and online tests here.
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Mathematics for JAMB
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