Chapter 8 ยท ICSE Class 8 Mathematics

Profit, Loss and Discount

Solve multi-step business problems involving successive discounts, and profit/loss expressed as a fraction of cost or selling price.

๐Ÿท๏ธ Chapter 8

A diagram showing cost price and selling price to illustrate profit A bar for cost price and a taller bar for selling price, with an arrow showing the profit as the difference between them Cost Price Selling Price Profit
8.1

Successive Discounts

When two discounts are applied one after another, the second discount is calculated on the already-reduced price, not the original price. This means two successive discounts don't simply add together.

1

An item marked โ‚น1000 gets a 10% discount, then a further 5% discount. Find the final price.

After 10%: 1000 โˆ’ 100 = 900. After 5% on 900: 900 โˆ’ 45 = โ‚น855

2

Are successive discounts of 20% and 10% the same as a single 30% discount?

No โ€” successive 20% then 10% gives a final price of 0.80 ร— 0.90 = 72% of original, which is a 28% discount overall, not 30%

8.2

Profit or Loss as a Fraction of CP or SP

Sometimes a problem describes cost price as a fraction of selling price, or vice versa. Setting up the relationship as an equation makes it possible to find the profit or loss percentage.

1

The cost price of an article is 4/5 of its selling price. Find the profit or loss percent.

Let SP = 5, so CP = 4. Profit = SP โˆ’ CP = 1. Profit% = (1/4) ร— 100 = 25%

2

A shopkeeper sells goods at 90% of the cost price. Find the loss percent.

Let CP = 100, SP = 90. Loss = 10. Loss% = (10/100) ร— 100 = 10%

Practice

Exercises

1. An item marked โ‚น2000 gets a 15% discount, then a further 10% discount. Find the final price.

2. Are successive discounts of 10% and 10% the same as a single 20% discount?

3. The cost price of an article is 3/4 of its selling price. Find the profit percent.

4. A shopkeeper sells goods at 80% of the cost price. Find the loss percent.

5. An article marked โ‚น1500 is sold after two successive discounts of 20% and 5%. Find the final selling price.