Solving Proportions and Decimals

In this video, Mr. J explains how to solve proportions involving decimals using cross multiplication. He provides two examples, demonstrating the step-by-step process of solving each proportion. The video also covers different ways to represent multiplication and offers tips on handling repeating decimals by rounding. The tutorial concludes with a summary of the key points discussed.

What method is used to solve proportions with decimals in this video?

• Direct division

• Subtraction method

• Cross multiplication

• Cross addition

In the first example, what is the initial equation given?

• X to nine tenths equals 18 and 8 tenths to 3 and 6 tenths

• X to three tenths equals 18 and 8 tenths to 9 tenths

• X to nine tenths equals 3 and 6 tenths to 18 and 8 tenths

• X to 18 tenths equals 9 and 8 tenths to 3 and 6 tenths

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CCSS.3.OA.A.1

Which of the following is NOT a way to represent multiplication?

• Using a dot

• Using an asterisk

• Using parentheses

• Using a plus sign

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CCSS.7.EE.B.3

What is the value of X in the first example after solving the equation?

• 3 and 6 tenths

• 5 and 7 tenths

• 4 and 7 tenths

• 6 and 9 tenths

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CCSS.7.EE.B.3

What is the purpose of cross multiplication in solving proportions?

• To subtract the numbers

• To find the average

• To add the numbers

• To create a one-step equation

In the second example, what is the initial equation given?

• 4 and 35 hundredths to X equals 7 and 9 tenths to 10 and 41 hundredths

• X to 4 and 35 hundredths equals 7 and 9 tenths to 10 and 41 hundredths

• 10 and 41 hundredths to 4 and 35 hundredths equals X to 7 and 9 tenths

• 4 and 35 hundredths to 7 and 9 tenths equals X to 10 and 41 hundredths

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CCSS.6.EE.B.7

What is the key step after cross multiplying to solve for X?

• Adding both sides

• Subtracting both sides

• Dividing both sides

• Multiplying both sides

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CCSS.6.NS.B.3

What is the approximate value of X in the second example after rounding?

• 5 and 73 hundredths

• 5 and 71 hundredths

• 5 and 72 hundredths

• 5 and 74 hundredths

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CCSS.5.NBT.B.7

Why is the approximate sign used in the second example?

• Because the equation was incorrect

• Because the decimal had repeating digits

• Because the multiplication was not accurate

• Because the division was not performed

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CCSS.5.NBT.A.4

What should you do if you encounter a long decimal or a repeating decimal?

• Multiply it by 10

• Round it to a given place

• Ignore it

• Divide it by 10

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CCSS.5.NBT.A.4