1. 1. ) Triangle ABC is similar to triangle XYZ. The length AB is 10
1.) Triangle ABC is similar to triangle XYZ. The length AB is 10. The length BC is 7. Find the length XY if the length YZ is 14.
2.) A blueprint scale is 1 in: 12 ft. The width of a building is 48 feet. What is the width of the building on the blueprint?
3.) Angie is using similar triangles to find the height of a tree. A stick that is 5 feet tall casts a shadow that is 4 feet long. The tree casts a shadow that is 22 feet long. How tall is the tree?

2. Proportions and Percent

3. “per cent” means “out of 100”
When setting up a proportion, always remember “is over of equals percent over 100”

4. Examples
1.) What percent of 75 is 60?
2.) What percent is 17 of 25?

5. 3.) Find 75% of 76.
4.) One hundred thirty-five is what percent of 27?

6. Try:
1.) What percent of 68 is 51?
2.) Find 24% of 120.
3.) 75% of p is 12. What is p?

9. A commission is money paid to a person or a company for making a sale
A commission is money paid to a person or a company for making a sale. Usually the commission is a percent of the sale amount.

10. Mr. Cortez earns a base salary of $26,000 plus a sales commission of 5%. His total sales for one year were $300,000. Find his total pay for the year.

11. I = P r t Simple Interest Paid Annually
Interest is the amount of money charged for borrowing money, or the amount of money earned when saving or investing money. Principal is the amount borrowed or invested. Simple interest is interest paid only on the principal.
Simple Interest Paid Annually I = P r t
Simple interest
Time in years
Principal
Interest rate per
year as a decimal

12. Find the simple interest paid for 3 years on a $2500 loan at 11
Find the simple interest paid for 3 years on a $2500 loan at 11.5% per year.

13. After 6 months, the simple interest earned on an investment of $5000 was $45. Find the interest rate.

15. A tip is an amount of money added to a bill for service
A tip is an amount of money added to a bill for service. it is usually a percent of the bill before sales tax is added. Sales tax is a percent of an item’s cost.

16. Sales tax and tips are sometimes estimated instead of calculated exactly. When estimating percents, use percents that you can calculate mentally.
Find 10% of a number by moving the decimal point one place to the left.
Find 1% of a number by moving the decimal point two places to the left.
Find 5% of a number by finding of 10% of the number.

17. Lunch at a restaurant is $27.88. Estimate a 15% tip.
Step 1 First round $27.88 to $30.
Step 2 Think: 15% = 10% + 5% % of $30 = $3.00
Move the decimal point one place left.
Step 3 Think 5% = 10% ÷ 2
= $3.00 ÷ 2 = $1.50
Step 4 15% = 10% + 5% = $ $1.50 = $4.50
The tip should be about $4.50.

18. The sales tax rate is 7.25%. Estimate the sales tax on a book that costs $19.97.
Step 1 First round 7.25% to 7% and $19.97 to $20.
Step 2 Think: 7% = 7(1%) 1% of $20 =$0.20
Move the decimal point two places left.
Step 3 7% = 7(1%)
= 7($0.20) = $1.40
The sales tax is about $1.40.

20. HW: p #13-29 odd, all

21. Bellwork 2/20/08
1.) What percent of 60 is 50?
2.) Find 25% of 160.
3.) 70% of p is 12. What is p?