Can we go on!

You have 5 minutes to complete check-up.

Lets Check!1. 8 to 52. 4 to 193. 6 to 234. 16 to 10 and 24 to 155. 75meter/30sec. 2.5m/sec6. $8.75 per scarf7. Danny8. 12 men

Writing and Solving Proportions• I can write and solve proportions using ratios

and algebra.

• Textbook Pages 412-416

Vocabulary• Proportion: is an equation that shows that two

ratios are equivalent.Ratio: 2 of 3 rows Ratio: 8 of 12 dots

Proportion : 2/3 = 8/12

Cross Products• Cross Product: when you multiply the numerator

of each ratio by the denominator of the other ratio.

• The cross products of proportions are equal to each other.

To see if two ratios form a proportion, check to see if the cross products are equal: 8 20 10 25 so multiply 25 time 8 and 10 time 20What you get is 200=200

Try someAre these proportions:10/16 = 5/8Yes3/8 = 15/40Yes3/5=12/18No

Solving Using Mental Math:

• When one of the numbers in a proportion is unknown, you can find the number by solving the proportion.

• Just ask yourself what did they do to one to get the other.

• 4 = 20 12 x Multiply by 5 X= 60

Try some

• 1/5 = z/20• 4• 8/3 = k/18• 48• 9/c=3/12• 36

Review

• Can someone remind me how we solve multiplication equations:

• We divide both sides by whatever number is with the variable.

• 3x = 18• Divide both sides by 3• X = 6

Solving using equations:• You can solve proportions by using cross

product and making an equation.• You cross multiply then solve for the variable.• 10 50 60 x Cross multiply. 10x = 3000 Solve by dividing both sides by 10X=300

You try some!• 91/x = 7/5• 7x= 455X=6524/36 = 10/x24x=360X= 159/6 = h/146h=126H=21

Practice

• Workbook Pages 105-106 odds