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Math · Grade 6 Math

Chapter 1: Ratios

Tape Diagrams and Ratio Problems

Drawing the parts before you count them.

Lesson
4
Time
About 18 minutes
0 of 9 done
Part 1 of 7Let's Learn

Step 1: Let's Learn

Read it, or press Listen and follow the words.

Watch the idea first — 57 seconds. Then read on, and try it yourself in the next step.

Share 30 sweets between two children in the ratio 2 : 3.

Count the parts

The bar has 2 parts for one child and 3 for the other, so 5 parts in all.

Find one part

5 parts make 30, so one part is 30 ÷ 5 = 6.

Then build each share

One child gets 2 parts, so 12. The other gets 3 parts, so 18. Together that is 30.

Step 2: Try It Yourself

Tap and try it out.

Two bars in the given ratio. Their total is shown below.
First share
Second share

18 is 6 more than 12.

Step 3: In Real Life

Splitting a prize

Two friends split 90 dollars in the ratio 2 to 1. Draw 3 equal bars. Each bar is 30. 60 and 30. The picture does the dividing.

Step 4: Watch an Example

One step at a time.

Watch Leo Share 40 in the Ratio 3 : 5

Leo shares 40 marbles in the ratio 3 : 5.

  1. Step 1

    He counts the parts: 3 and 5 make 8 parts.

Step 5: Your Turn

Practice makes it stick.

The Sweets

Problem 1 of 3

Share 30 in the ratio 2 : 3. What is the smaller share?

The Money

Problem 2 of 3

Share 60 pounds in the ratio 1 : 5. What is the larger share?

pounds

The Difference

Problem 3 of 3

Share 45 in the ratio 4 : 5. How much bigger is the larger share?

Count the Parts

1 of 4

Share 24 in the ratio 1 : 2. What is the smaller share?

2 of 4

Share 35 in the ratio 2 : 5. What is the larger share?

3 of 4

Share 50 in the ratio 3 : 7. What is one part worth?

4 of 4

Share 36 in the ratio 4 : 5. What is the smaller share?

Step 6: Quick Check

Show what you know.

Question 1 of 2

Share 48 in the ratio 1 : 3. What is the larger share?

Question 2 of 2

To share a total in a ratio, what do you find first?

What You Learned

  • Draw the ratio as parts of a bar.
  • Divide the total by the number of parts to find one part.
  • Then build each share from the parts it has.
For the grown-up

What a tape diagram showsDraw one box for each part of the ratio: 3 boxes for red and 2 for blue. Every box is the same size, whatever that size turns out to be. The picture holds the relationship steady while you work out what one box is worth.

Find the value of one boxIf a 3 : 2 mix makes 40 liters altogether, there are 5 boxes and 40 ÷ 5 = 8 liters per box. So red is 3 × 8 = 24 and blue is 2 × 8 = 16. Almost every ratio problem reduces to finding what one box is worth.

When the difference is givenIf there are 12 more red than blue in a 3 : 2 mix, the difference is 1 box, so a box is 12. Red is 36 and blue is 24. The diagram tells you which quantity corresponds to the number you were given, which is what makes these problems tractable.

Check against the original ratioOnce you have both amounts, reduce them: 36 : 24 reduces to 3 : 2. If it does not match the ratio you were given, something went wrong. This check is quick and it verifies the answer rather than the arithmetic.

Draw the parts as boxesRed to blue is 3 : 2, and there are 30 counters. Draw 3 boxes for red, 2 for blue. Five boxes in all. 30 ÷ 5 = 6 in each box. Red: 3 × 6 = 18. Blue: 2 × 6 = 12. Check: 18 + 12 = 30.