Understanding Proportions through Cross Multiplication

Match the following

• 21

• 
• 67.5

• 
• 36

• 

Answer explanation

1) Cross Multiply

2) Divide

Tags

CCSS.7.RP.A.2C

What is the purpose of cross multiplication in solving proportions?

• To multiply numbers across the proportion

• To find the value of the unknown variable

• To subtract the known values from each other

• To add values on either side of the equation

What mathematical operation is primarily used to solve proportions in this video?

• Cross multiplication

• Addition

• Subtraction

• Multiplication

What is the first step in solving a proportion using cross multiplication?

• Isolate the variable

• Draw arrows to represent cross multiplication

• Divide both sides by the coefficient of the variable

• Add the values on both sides

In the first example, what is the value of N when 4/10 equals N/25?

• 10

• 20

• 5

• 15

How do you isolate the variable N in the equation 10N = 100?

• Subtract 10 from both sides

• Multiply both sides by 10

• Divide both sides by 10

• Add 10 to both sides

What is the result of cross multiplying 4/10 and N/25?

• 100 = 10N

• 25 = 4N

• 10 = 25N

• 40 = N

What does X equal when 8/20 equals X/15?

• 10

• 8

• 6

• 4

How is the value of X found in the equation 20X = 120?

• By adding 20 to both sides

• By dividing both sides by 20

• By subtracting 20 from both sides

• By multiplying both sides by 20

What is the equivalent of 6/8 in twentieths?

• 20/20

• 18/20

• 15/20

• 12/20