8 Applications of Percentages Revision

A survey finds that 75% of 3400 Australians own at least one mobile phone. What is the expected number of these Australians who own at least 1 mobile phone?

• 850

• 255

• 785

• 1700

• 2550

Answer explanation

This question is asking us to find 75% of 3400.

We can solve this two ways:

75% x 3400 = 2550

OR

(75/100) x3400 2550

In a survey of 760 students who travel to university, 20% catch the train and 15% catch the bus. How many do not use the train or bus?

• 152

• 114

• 494

• 266

• 760

Answer explanation

This question is asking us how many people DO NOT travel by train or bus.

First, we need to add the two percentages:

20% + 15% = 35%

Then we need to find how many people are not included in that 35%:

100% - 35% = 65%

Finally, we find what 55% of

760 is.

65% x 760 = 494

GST is charged at a rate of 10% in Australia. If the cost for a coat is $89.00 before tax, what will the final cost be?

• $8.98

• $8.89

• $8.90

• $97.09

• $97.90

Answer explanation

This question is asking us to work out the total price INCLUDING GST.

We must first calculate how much GST is being charged on the purchase.

10% of $89 is $8.90

Then we add the GST amount to the price.

$89 + $8.90 = $97.90

A set of car tyres costing $550 was discounted by 15% at a sale. What is the discounted price of the tires?

• $82.50

• $467.50

• $501.04

• $97.58

Answer explanation

This question is asking us to find a discounted price on an item.

We must first find the amount which will be discounted from the price.

15% of $550 is $82.50

THen we can subtract the discount amout from the original price to get our new pice.

550 - 82.5 =467.5

A flight from Melbourne to Sydney was discounted from $499 to $99. By what percentage was it reduced?

• 20%

• 30%

• 50%

• 60%

• 80%

Answer explanation

This question is asking us to find the discount %.

First, we must find the difference between the original and discounted price.

499 - 99 = $400

Then we find the percentage by dividing the difference by the original price.

400/499 x 100 = 80.16%

A used car was bought for $5000 and repaired. It was sold 6 months later for $6200. What is the percentage profit made on the sale?

• 24%

• 25%

• 16%

• 17%

• 20%

Answer explanation

The question is asking you to find the profit %.

first we need to find the difference between the two prices.

6200 - 5000 = $1200

Then we find the percentage by dividing the difference by the original price

1200/5000 x 100 = 24%

A 10% discount reduced the price of a T-shirt by $1.90. What was the original price?

• $13

• $15

• $18

• $19

• $25

Answer explanation

This question is asking us to find the original price using the percentage and discounted amount.

First we need to work out how many 10%s go into 100%.

In this case 10 groups of 10% make 100%.

10% x 10 = 100%

Then we use the same number to multiply the discounted amount.

10 x 1.9 = $19

Trevor’s sports shop had a sale with 15% off the usual price of surfboards. If the original price of a surfboard was $2800, what will the sale price be?

• $420

• $2,800

• $2,380

• $684

• $1,549

Answer explanation

This question wants us to find the discounted amount.

The first step is to find the discount amount by finding 15% of 2800:

15% x 2800 = 420

Then we subtract the discount amount from the original price to find the discounted price.

2800 - 420 = $2380

Noriko worked in a dress shop. She bought a dress for $56. How much did she sell the dress for if she made a 115% profit?

• $176.40

• $120.40

• $8.40

• $64.40

• $47.60

Answer explanation

This question is asking us to find the selling price of the dress.

First, we need to find the profit amount by finding 115% of $56.

115% x 56 = $64.4

THen we have to add the profit amount to the cost price.

56 + 64.4 = $120.40

An outdoor living shop operates on a profit margin of 40%. How much would the shop have paid for a tent that sells for $350?

• $490

• $250

• $350

• $210

• $110

Answer explanation

This question is asking us to find the Cost price of the tent given the selling price and the profit %.

Find what percentage of cost the selling price is.

100% + 40% = 140%

divide the selling price by the percentage.

350 / 140% = $250