Test
Percentage change and interest
Dynamic tasks on discounts, repeated percentage changes, simple interest and financial choices. Also distinguishes percent from percentage points.
Time left: 00:00:00
Sample questions
- An item cost ___. Its price increased by ___% in each of two consecutive years. What was the price after the second increase?
- An item cost ___. A ___% discount was applied. What is the new price?
- The price was ___. It was first increased by ___% and then decreased by ___%. What is the final price?
- A deposit of ___ earns ___% simple interest per year. What will the balance be after ___ years?
- After a ___% discount, an item costs ___. What was its original price?
Percentage change and interest
To increase a quantity by p%, multiply by 1 + p/100; to decrease it, multiply by 1 − p/100. Successive changes are applied one after another, so equal percentage increases and decreases do not cancel.
Interest
Simple interest is calculated from the original principal. Distinguish the interest earned from the final amount. A percentage point is the difference between two percentage rates, not a relative percentage change.
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