Worked example
An amount of $100 earns simple interest at 5% per year for 2 years. How many dollars of interest are earned?
Answer & why
Answer: 10
Simple interest = principal × rate × time: 100 × × 2 = 10 dollars.
Grade 7 · Math
Calculate simple interest
Calculate interest on an unchanged principal over whole years.
8 authored questions + worked example
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All questions
All 8 authored questions for this skill.
Question 1
An amount of $600 earns simple interest at 2% per year for 5 years. How many dollars of interest are earned?
- 62
- 60
- 59
- 61
A hint
Simple interest is calculated on the original principal each year.
Answer & why
Answer: 60
Simple interest = principal × rate × time: 600 × × 5 = 60 dollars.
Question 2
An amount of $150 earns simple interest at 4% per year for 2 years. How many dollars of interest are earned?
- 12
- 11
- 13
- 14
A hint
Simple interest is calculated on the original principal each year.
Answer & why
Answer: 12
Simple interest = principal × rate × time: 150 × × 2 = 12 dollars.
Question 3
An amount of $100 earns simple interest at 5% per year for 2 years. How many dollars of interest are earned?
- 11
- 9
- 10
- 12
A hint
Simple interest is calculated on the original principal each year.
Answer & why
Answer: 10
Simple interest = principal × rate × time: 100 × × 2 = 10 dollars.
Question 4
An amount of $200 earns simple interest at 4% per year for 3 years. How many dollars of interest are earned?
- 24
- 26
- 23
- 25
A hint
Simple interest is calculated on the original principal each year.
Answer & why
Answer: 24
Simple interest = principal × rate × time: 200 × × 3 = 24 dollars.
Question 5
An amount of $300 earns simple interest at 6% per year for 2 years. How many dollars of interest are earned?
- 38
- 36
- 35
- 37
A hint
Simple interest is calculated on the original principal each year.
Answer & why
Answer: 36
Simple interest = principal × rate × time: 300 × × 2 = 36 dollars.
Question 6
An amount of $250 earns simple interest at 8% per year for 1 years. How many dollars of interest are earned?
- 19
- 20
- 21
- 22
A hint
Simple interest is calculated on the original principal each year.
Answer & why
Answer: 20
Simple interest = principal × rate × time: 250 × × 1 = 20 dollars.
Question 7
An amount of $500 earns simple interest at 3% per year for 4 years. How many dollars of interest are earned?
- 60
- 59
- 61
- 62
A hint
Simple interest is calculated on the original principal each year.
Answer & why
Answer: 60
Simple interest = principal × rate × time: 500 × × 4 = 60 dollars.
Question 8
An amount of $400 earns simple interest at 5% per year for 3 years. How many dollars of interest are earned?
- 60
- 61
- 62
- 59
A hint
Simple interest is calculated on the original principal each year.
Answer & why
Answer: 60
Simple interest = principal × rate × time: 400 × × 3 = 60 dollars.