Lesson 8.3 Percentage in Real-World Context

Lesson 8.3: Percentage in real-world contexts

By Eunice Dimasangal

A. Profit and Loss, page 23

A manufacturer produces goods at a certain cost.

If the goods are sold at a price higher than the cost price, the manufacturer makes a profit (or gain).

However, if the manufacturer sells the goods at a price lower than the cost price, he suffers a loss.

Multiple Choice

Based on the definitions in the previous slide, which of the following can be used to compute for profit?

• Profit = selling price - cost price

• Profit = selling price + cost price

• Profit = selling price x cost price

• Profit = cost price - selling price

Multiple Choice

Which of the following is correct?

• Loss = cost price - selling price

• Loss = selling price - cost price

• Loss = cost price + selling price

• Loss = cost price x selling price

Profit/Loss as a percentage of cost price / selling price

A bag costs $28. 

If the bag is sold for $35, express the profit as a percentage of the cost price.

Multiple Choice

A bag costs $28. 

If the bag is sold for $24.50, express the loss as a percentage of the selling price in 3 significant figures.

• 14.3%

• 1.43%

• 0.143%

Finding cost price

A bookseller gains 30% on the cost price by selling a book for $65.
Calculate the cost price of the book.

B. Discount

To clear the merchandise in stock (such as defective merchandise, overstocked items or discontinued models), the items are usually sold at a lower price, called the sale price.

The original selling price is called the marked price.

The discount is the difference between the marked price and the sale price.

Multiple Choice

Which of the following is correct about discount?

• Discount = marked price - sale price

• Discount = marked price + sale price

• Discount = marked price x sale price

Percentage Discount

A watch priced at $160 is sold for $100. Find the percentage discount.

Multiple Choice

The marked price of a washing machine is $600. A discount of 6% is given during a sale. Find the sale price of the washing machine.

• $564

• $465

• $546

• $456

Finding marked price

A sculpture is sold for $533 after a discount of 18%.

Calculate the marked price of the sculpture.

C. Goods and Services Tax (GST)

The various taxes collected by the Singapore government fund government expenditure on national defence, education, and building of infrastructure such as roads.

Examples of taxes include Goods and Services Tax (GST) and income tax.

GST is paid in addition to the price of goods and services.

Finding selling price inclusive of GST

A piece of furniture costs $640 before GST. Assuming that GST is at 7%, calculate the total amount of money Devi has to pay for the piece of furniture.

Multiple Choice

An article costs $85 before GST. Assuming that GST is at 7%, find the total amount of money a man has to pay for the article.

• $90.95

• $5.95

• $95.90

• $79.05

D. Commission

A commission is the payment an agent receives for selling or buying something on behalf of another party.

It is usually given as a percentage of the cost price or the selling price.

Finding Commission

A property agent sells a house for $320 000, of which he receives a commission of 1.5%. Calculate the amount of commission the agent receives.

Open Ended

Reflection: How can my knowledge of percentage help me in everyday situations?

Rewrite your answer in your notebook after submitting your answer here. You have 5 minutes to do this.

Worksheet 8C