If a price (or anything else for that matter) changes, we often want to find what percentage it has changed by. We can always do this using the formula:

Example

Exercise

Let’s complete exercise 1 from page 254 of the core textbook:

The answers are below:

A very similar approach lets us find out the percentage profit (or loss) made when an item is sold. We divide the difference between the sales price and the cost price by the cost price. Please remember that we always divide by the original amount, to find the percentage change. In this case the original amount is the cost price of the item.

Example

A car is bought for $60,000 and then sold for $75,000. What is the percentage profit on the sale?

Exercise

Let’s complete exercise 2 from page 254 of the core textbook:

The answers are below:

Extension exercise

Let’s try the more difficult questions below (from exercise 4 in the core textbook):

The answers are below: