Monthly: Error Analysis & Misconceptions

Mathematics
Grade 8
13 questions
~26 mins
1 views0 downloads

About This Worksheet

A worksheet focusing on understanding and correcting misconceptions related to monthly compound interest calculations, including error analysis and real-world applications.

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Monthly: Error Analysis & Misconceptions

Subject: MathematicsGrade: Grade 8
Name:
Date:
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Untitled Worksheet

Grade Grade 8
A

Fluency & Practice

Answer all questions. Show your working in the grid spaces provided.
1.
Calculate the compound interest earned after 1 year on a principal of $1200 at an annual interest rate of 6%, compounded monthly.
[3 marks]
2.
What is the monthly interest rate if the annual rate is 12%?
[2 marks]
3.
A principal of $2000 earns interest compounded monthly at 0.5%. What is the interest after 6 months?
[3 marks]
4.
Calculate the amount accumulated after 3 months on $1500 at an annual rate of 9%, compounded monthly.
[3 marks]
B

Problem Solving & Reasoning

Answer all questions clearly, explaining your reasoning where appropriate.
1.
A savings account has a principal of $2500 with an annual interest rate of 8%, compounded monthly. How much interest will accrue after 9 months? Show your calculations.
[4 marks]
2.
Explain why using the annual interest rate divided by 12 might lead to errors if not applied correctly in monthly compounding.
[3 marks]
3.
A person invests $1000 at an annual interest rate of 6%, compounded monthly. After 1 year, they find the interest is less than expected. What common mistake might they have made?
[4 marks]
C

Real-world Applications

Solve these contextual problems involving monthly compound interest.
1.
A student deposits $500 into a savings account earning 5% annual interest, compounded monthly. How much will they have after 2 years?
[4 marks]
2.
A business invests $10,000 at 7% interest per year compounded monthly. How much interest does the business earn after 6 months?
[3 marks]
D

Challenge & Extension

Attempt these more advanced problems. Show detailed working.
1.
A principal of $3000 is invested at 9% annual interest, compounded monthly. What will be the total amount after 18 months? Calculate the interest earned.
[4 marks]
2.
Design a scenario where monthly compounding results in more interest earned than yearly compounding, and explain why this occurs.
[4 marks]
E

Mixed Review & Error Analysis

Review the following common mistakes related to monthly compound interest. Identify and correct the errors.
1.
A student incorrectly uses the annual interest rate directly as the monthly rate without dividing by 12. Explain why this leads to an overestimation, and correct the calculation for a principal of $1500 at 12% annual rate over 3 months.
[4 marks]
2.
A teacher states that interest earned after 6 months at 6% annual rate compounded monthly is the same as at simple interest. Is this correct? Justify your answer and show the calculation.
[4 marks]

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Details

Created
1/1/2026
Updated
1/1/2026
Type
worksheet