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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.B.7

Apply and extend previous understandings of division to divide unit fractions by whole numbers and whole numbers by unit fractions.

5.NF.B.7a

A. Interpret division of a unit fraction by a non-zero whole number, and compute such quotients. Use the relationship between multiplication and division to justify conclusions.

5.NF.B.7b

B. Interpret division of a whole number by a unit fraction, and compute such quotients. For example, create a story context for 4 ÷ (1/5), and use a visual fraction model to show the quotient. Use the relationship between multiplication and division to justify conclusions (e.G., 4 ÷ (1/5) = 20 Because 20 x (1/5) = 4).

5.NF.B.7c

C. Solve problems in real-world context involving division of unit fractions by non-zero whole numbers and division of whole numbers by unit fractions, using a variety of representations.

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