7th Grade Chapter 1-2 Review

7th Grade Chapter 1-2 Review

Proportional Relationships with tables

• Turn the first ratio from the table into a fraction y/x

• Simplify your fraction

• Is that fraction equivalent to every other ratio in the table?

First table it's  $\frac{5}{20}=\frac{1}{4}$  

Is  $\frac{6}{24}=\frac{1}{4}$  ? Yes, so the proportion is  $\frac{1}{4}$  
In the second table  $\frac{10}{5}=\frac{2}{1}or\ 2$  
Is  $\frac{18}{6}=\frac{2}{1}$  ? No so it is not proportional

Multiple Choice

Was table 1 proportional?

• Yes

• No

Multiple Choice

Was table 2 proportional?

• Yes

• No

Direct Variation from Ordered Pairs

• This is the same as your proportional relationship

• You need to write an equation for the direct variation explaining that y is __ times x

Direct variation

Which table is a direct variation? Table 2 is a direct variation y=what times x?
 $y=\frac{2}{5}x$  

Multiple Choice

Was table 1 a direct variation?

• Yes

• No

Multiple Choice

Was table 2 a direct variation?

• Yes

• No

The Percent Equation

• the word "of" becomes a multiplication sign

• the word "is" becomes an equals sign

• Solve for the unknown

• 25 is 50% of what number

• 25= 0.5 x _

•  $25\div0.5=$  

• 50

Total cost including tax or markup

• To find the tax or markup you find the percent of the amount

• Add the percent back to the amount

• The camera is $533.98. Tax is 7.5%. Round to the nearest cent

• 533.98 x 0.075

• 533.98 x 0.075 = 40.05

• 533.98 + 40.05

• 533.98 + 40.05 = 574.03

Finding Sale Price

• A table is being sold at a 38% discount. The sale price is $465. What was the price yesterday

• Subtract the percent from 100% 100-38=62

• then use percent equation.

• 465 is 62% of what number

• 465 = 0.62 x what

•  $465\div0.62\$  

• 750

Simple Interest

• Use the interest equation I=prt

• Interest = principal (original amount) x rate x time

• Ivanna invested $6000 for 3 years and was paid $1620 in interest what was the interest rate?

• 1,620=6,000 x 3 x r

• 1,620 = 18,000r

•  $1,620\div18,000=$  

• 9% interest