MULTIPLYING RATIONAL NUMBERS WORD PROBLEMS WORKSHEET

Problem 1 : 

A student can eat 1/8 of a pizza. If there are 40 students in David's class, how many pizzas does David need ?

Problem 2 : 

There are 450 students in school. If 4/9 th of the students are boys, find the number girls in the school. 

Problem 3 : 

The science teacher is filling her new fish aquarium. The aquarium holds 40 gallons. If she fills the aquarium 4/5 of the way full, how many gallons will she need?

Problem 4 :

The science teacher is filling her new fish aquarium. The aquarium holds 40 gallons. If she fills the aquarium 4/5 of the way full, how many gallons will she need?

Problem 5 :

In a test consisting of 60 questions, Tim answered 3/4 of the questions correctly. How many questions did Tim answer correctly ?

Problem 6 :

The price of a shirt is 2/15 of the cost of a suit. If the suit costs $375, find the price of the shirt ?

Problem 7 :

Only 3/8 of a class brought lunch to school yesterday. If there are 24 students in the class, how many brought lunch to school ?

Problem 8 :

A store has 6 boxes of pencils. Davey buys 1  1/3 boxes and Erik buys 2  1/2 times as many boxes as Davey. How many boxes are left in the store ?

Detailed Answer Key

Problem 1 : 

A student can eat 1/8 of a pizza. If there are 40 students in David's class, how many pizzas does David need ?

Solution :

To find how many pizzas that David needs, we have to multiply 40 and 1/8. 

Step 1 : Multiply 40 by 1/8

40 x 1/8  

Step 2 : Simplify

5 x 1/1

Step 3 : Multiply 

5 x 1/1  =  5    

So, David needs 5 pizzas. 

Problem 2 : 

There are 450 students in school. If 4/9 th of the students are boys, find the number girls in the school. 

Solution :

If 4/9 of the students are boys, then 5/9 th of the students are girls. Because 9 - 4  =  5.

To find number of girls, we have to multiply 450 by 5/9. 

Step 1 : Multiply 450 by 5/9

450 x 5/9     

Step 2 : Simplify

50 x 5/1

Step 3 : Multiply 

50 x 5/1  =  250    

So, there are 250 girls in the school. 

Problem 3 : 

The science teacher is filling her new fish aquarium. The aquarium holds 40 gallons. If she fills the aquarium 4/5 of the way full, how many gallons will she need?

Solution :

If 4/5 of the aquarium is filled, then 1/5 th of the aquarium to be filled to make it full. Because 5 - 4  =  1.

To find number of gallons, we have to multiply 40 by 1/5. 

Step 1 : Multiply 40 by 1/5

40 x 1/5     

Step 2 : Simplify

8 x 1/1

Step 3 : Multiply 

8 x 1/1  =  8    

So, the science teacher needs 8 gallons to make the aquarium full. 

Problem 4 : 

A baker needs to make 8 batches of cookies for a party. If each batch requires 2 3/4 cups of flour, how many cups will he need ?

Solution :

To find number of cups needed, we have to multiply 8 by 2 3/4. 

Step 1 : Multiply 8 by 2 3/4

8 x 2 3/4     

Step 2 : Simplify

8 x 11/4  =  2 x 11/1

Step 3 : Multiply 

2 x 11/1  =  22    

So, the baker needs 22 cups of flour to make 8 batches of cookies. 

Problem 5 :

In a test consisting of 60 questions, Tim answered 3/4 of the questions correctly. How many questions did Tim answer correctly ?

Solution :

Total number of questions = 60

Fraction part of questions answered correctly = 3/4

Number of questions answered correctly = 3/4 of 60

= (3/4) x 60

= 45

So, 45 questions are answered correctly.

Problem 6 :

The price of a shirt is 2/15 of the cost of a suit. If the suit costs $375, find the price of the shirt ?

Solution :

Cost of suit = $375

Price of shirt = 2/15 of the cost of a suit

= (2/15) x 375

= 2 x 25

= $50

So, cost of shirt is $50.

Problem 7 :

Only 3/8 of a class brought lunch to school yesterday. If there are 24 students in the class, how many brought lunch to school ?

Solution :

Total number of students in the class = 24

Part of the students who brought lunch to school = 3/8

Number of students who brought lunch to school = 3/8 of 24

= (3/8) x 24

= 3 x 3

= 9 students

So, 9 students who brought lunch to school yesterday.

Problem 8 :

A store has 6 boxes of pencils. Davey buys 1  1/3 boxes and Erik buys 2  1/2 times as many boxes as Davey. How many boxes are left in the store ?

Solution :

Number of boxes Erik buys :

= 2  1/2 x 1  1/3

= 5/2 x 4/3

= 20/6

= 10/3

Number of boxes left : 

= 6 - 10/3

= (18 - 10)/3

= 8/3

= 2.6

Approximately 3 boxes are left.

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