Solving Proportions using Cross Multiply and Divide

Solving Proportions using Cross Multiply and Divide

I can get ready for Similarity!

Why does the cross multiply and divide method work?

It's kind of like creating equivalent fractions.

Multiple Choice

What is the first step in using the cross multiply and divide method to solve this proportion?

 $\frac{k}{4}=\frac{3}{8}$  

•  $4k=3\cdot8$  

•  $3\cdot4=8\cdot k$  

Multiple Select

Solve this proportion:

 $\frac{k}{3}=\frac{4}{8}$  

•  $k=1.5$  

•  $k=\frac{12}{8}$  

•  $k=\frac{32}{3}$  

•  $k=6$  

Multiple Choice

Solve this proportion:

 $\frac{z}{7}=\frac{24}{28}$  

• z=6

• z=11

• z=4

• z=168

Multiple Choice

Solve this proportion:

 $\frac{n}{10}=\frac{4.7}{5}$  

• n=2

• n=9.4

• n=2.35

• n=0.5

Open Ended

How is this problem different? How do you think the steps for solving will change?

 $\frac{\left(x-1\right)}{2}=\frac{12}{8}$  

Multiple Choice

 $\frac{12}{5}=\frac{5}{n}$  

•  $n=12$  

•  $n=\frac{25}{12}$  

Multiple Choice

 $\frac{7}{3}=\frac{4}{t}$  

•  $t=\frac{12}{7}$  

•  $t=\frac{28}{3}$  

•  $t=1.7$  

•  $t=9.3$  

Multiple Choice

 $\frac{10.8}{d}=\frac{6}{10}$  

•  $d=6.48$  

•  $d=5.5$  

•  $d=18$  

IXL, Algebra I, C.5

https://www.ixl.com/math/algebra-1/solve-proportions

Get it as high as you can by the end of class!