MULTIPLYING DECIMALS WORD PROBLEMS

Problem 1 :

Each batch of cookie mix need 0.5 cups of sugar and each batch can make 20 cookies. If Alex is making 5 batches of cookies, how much sugar does he need?

Solution :

Amount of sugar needed for 1 batch of cookie = 0.5 cups

Amount of sugar needed for 5 batches of cookie :

= 5 x 0.5

= 2.5 cups

Problem 2 :

Each cookie needs 0.03 cups of sugar and each batch can make 30 cookies. If Lily is making 4 batches of cookies, how much sugar does she need?

Solution :

Number of cookies in each batch = 30

Number of cookies in 4 batches :

= 4x 30

= 120

Amount of sugar needed for 1 cookie = 0.03 cups

Amount of sugar needed for 120 cookies :

= 120 x 0.03

=  3.6 cups

Problem 3 :

Gasoline mileage of a car is 24.4 miles per gallon. How many miles will the car travel with 2.5 gallons of gasoline?

Solution :

Given : Gasoline mileage of a car is 24.4 miles per gallon.

That is, the car can travel 24.4 miles with 1 gallon of gasoline.

Distance travelled by the car with 2.5 gallons of gasoline :

= 2.5 x 24.4

= 61 miles

Problem 4 :

The cost of an oil is $2.80 per liter. Find the cost of 2.8 liters of oil.

Solution :

Given : The cost of an oil is $2.80 per liter.

That is, the cost of 1 liter of oil is $2.80.

Cost of 2.8 liters of oil :

= 2.8 x 2.80

= $7.84

Problem 5 :

The cost of 3 pencils is $1.20. Find the cost of 8 pencils.

Solution :

Given : The cost of 3 pencils is $1.20.

Cost of 1 pencil :

= 1.20/3

= $0.40

Cost of 8 pencils :

= 8 x 0.40

= $3.2

Problem 6 :

If the cost of a pen is $2.75, a book is $25.75 and a bag is $30.50, then find the total cost of 5 books, 3 pens and 2 bags. 

Solution :

Total cost of  5 books, 3 pens and 2 bags : 

= 5(25.75) + 3(2.75) + 2(30.50)

= 128.75 + 8.25 + 61

= $198

Problem 7 :

The cost of a camera without tax is $125. If the tax is 5%, find the cost of the camera after the tax.

Solution :

Cost of the camera after the tax :

= (100 + 5) % of 125

= 105% of 125

= 1.05 x 125

= $131.25

Problem 8 :

The cost price of a product $30 and the selling price is 15% more than the cost price. Find the selling price of the product.

Solution :

Selling price of the product :

= (100 + 15) % of 30

= 115% of 30

= 1.15 x 30

= $34.50

Problem 9 :

The cost price of an item is $60 and it is sold at a loss of 20%. Find the selling price of the item.

Solution :

Selling price of the product :

= (100 - 20) % of 60

= 80% of 60

= 0.8 x 60

= $48

Problem 10 :

The price of a book is $80 and it is sold at 25% discount. If the tax is 7%, how much has to be paid for the book?

Solution :

Original price of the book = $80

The price of the book after 25% discount :

= (100 - 25) % of 80

= 75% of 80

= 0.75 x 60

= $48

The price of the book after 25% discount and 7% tax :

= (100 + 7) % of 48

= 107% of 48

= 1.07 x 48

= $51.36

$51.36 has to be paid for the book.

Problem 11 :

Adam is a salesman in a store and he is paid $400 salary per week and 2.5% commission on sales he makes. Last week, if he had made $4856 sales, find the amount of money he earned.

Solution :

Amount of money earned by Adam last week :

= 400 + 2.5% of 4856

= 400 + 0.025x4856

= 400 + 121.40

= $521.40

Problem 12 :

If the radius of a circle is 4.6 cm, find its circumference using π ≈ 3.14.

Solution :

Circumference of a circle = 2πr

Substitute π ≈ 3.14 and r = 4.6.

≈ 2(3.14)(4.6)

= 28.888

Circumference of the circle is about 28.888 cm.

Problem 13 :

If the radius of a circle is 7.2 cm, find its area using π ≈ 3.14.

Solution :

Circumference of a circle = πr²

Substitute π ≈ 3.14 and r = 7.2.

≈ 2(3.14)(7.2)

= 45.216

Area of the circle is about 45.216 cm².

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