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8.12 Story problems with dividing fractions and whole numbers

Lesson

Are you ready?

Do you remember how to divide whole numbers by unit fractions, and unit fractions by whole numbers?

What is $4\div\frac{1}{14}$4÷​114?

Find the value of the following division:

  1. What is $\frac{1}{4}\div12$14÷​12?

Learn

When a problem is given as a story or description, we first want to determine what value we are trying to solve for - this will often be in the last sentence. After that, we look back through the rest of the story to find:

  • any numbers/values that we know
  • a keyword that will tell us what operation to use

 

When the values in a story problem involve a division, make sure you are dividing the values the right way around! For example, if $6$6 cups of flour are poured into $\frac{1}{2}$12 cup sized containers, we can find the total number of containers needed by a division. We would need to divide the total number of cups, $6$6, by the size of each container, which is $\frac{1}{2}$12 of a cup, and we would get $6\div\frac{1}{2}=6\times2=12$6÷​12=6×2=12 containers.

Apply

Question 1

A $\frac{1}{2}$12 L bottle of soda is poured equally into $5$5 cups.

What is the liquid volume of soda in each cup?

Question 2

$6$6 kg of fruit is being shipped in boxes.

If each box holds $\frac{1}{4}$14 of a kg of fruit, how many boxes are needed?

Remember!

Make sure to read the whole question before attempting to solve the problem.

When dividing two values, make sure that the order of the division makes sense.

Outcomes

5.NF.7

Apply and extend previous understandings of division to divide unit fractions by whole numbers and whole numbers by unit fractions. Use strategies to divide fractions by reasoning about the relationship between multiplication and division. Division of a fraction by a fraction is not a requirement at this grade.

5.NF.7.a

Interpret division of a unit fraction by a non-zero whole number, and compute such quotients.

5.NF.7.b

Interpret division of a whole number by a unit fraction, and compute such quotients.

5.NF.7.c

Solve real world problems involving division of unit fractions by non-zero whole numbers and division of whole numbers by unit fractions, for example, by using visual fraction models and equations to represent the problem.

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