Presentation on theme: "Applications of Percents"— Presentation transcript:
1 Applications of Percents 2-9Applications of PercentsHolt Algebra 1Warm UpLesson PresentationLesson Quiz
2 Warm Up 1. Write 0.03 as a percent. 2. Write as a decimal. Find each value. Round to the nearest tenthif necessary.3. Find 10% of 53.Solve for x.5. 40 = (x) (20)3%0.0454. Find of 18.104.22.168= (36) (x)438
3 Objectives Use common applications of percents. Estimate with percents.
5 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.
6 Caution!You must convert a percent to a decimal or a fraction before doing any calculations with it.
7 Example 1: Business Application 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.total pay = base salary + commissionWrite the formula for total pay.= base + % of total salesWrite the formula for commission.= 26, % of 300,000Substitute values given in the problem.= 26,000 + (0.05)(300,000)Write the percent as a decimal.= 26, ,000Multiply.= 41,000Add.Mr. Cortez’s total pay was $41,000.
8 Check It Out! Example 1A telemarketer earns $350 per week plus 12% commission on sales. Find her total pay for a week in which her sales were $940.total pay = base salary + commissionWrite the formula for total pay.= base + % of total salesWrite the formula for commission.= % of 940Substitute values given in the problem.= (0.12)(940)Write the percent as a decimal.=Multiply.=Add.The telemarketer’s total pay was $
9 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. Principle is the amount borrowed or invested. Simple interest is interest paid only on the principle.Simple Interest Paid AnnuallyI=PrtSimple interestTime in yearsPrincipleInterest rate peryear as a decimal
10 Example 2A: Financial Application Find the simple interest paid for 3 years on a $2500 loan at 11.5% per year.I = PrtWrite the formula for simple interest.I = (2500)(0.115)(3)Substitute known values. Write the interest rate as a decimal.I =Multiply.The amount of interest is $
11 Example 2B: Financial Application After 6 months, the simple interest earned on an investment of $5000 was $45. Find the interest rate.Write the formula for simple interest.I = PrtSubstitute the given values.Multiply Since r is multiplied by 2500, divide both sides by 2500 to undo the multiplication.45 = 2500r0.018 = rThe interest rate is 1.8%.
12 Helpful HintWhen you are using the formula I= Prt to find simple interest paid annually, t represents time in years. One month is year.
13 Check It Out! Example 2aFind the simple interest earned after 2 years on an investment of $3000 at 4.5% interest earned annually.Write the formula for simple interest.I = PrtI = (3000)(0.045)(2)Substitute the given values.Multiply.I = 270The interest earned is $270.
14 Check It Out! Example 2bThe simple interest paid on a loan after 6 months was $306. The annual interest rate was 8%. Find the principle.Write the formula for simple interest.I = Prt306 = (P)(0.08)Substitute the given values.Multiply Since P is multiplied by 0.04 , divide both sides by 0.04.306 =.04P7650 = PThe remaining principle is $7650.
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 Example 3A: Estimating with Percents Lunch at a restaurant is $ Estimate a 15% tip.Step 1 First round $27.88 to $30.Step 2 Think: 15% = 10% + 5% % of $30 = $3.00Move the decimal point one place left.Step 3 Think 5% = 10% ÷ 2= $3.00 ÷ 2 = $1.50Step 4 15 = 10% + 5% = $ $1.50 = $4.50The tip should be about $4.50.
18 Example 3B: Estimating with Percents 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.Move the decimal point two places left.Step 2 Think: 7% = 7(1%) 1% of $20 =$0.20Step 3 7% = 7(1%)= 7($0.20) = $1.40The sales tax is about $1.40.
19 Helpful HintA 6.25% sales tax rate means that for every $100 you spend, you would pay $6.25 in sales tax.
20 Check It Out! Example 3aEstimate a 15% tip on a check for $21.98.Step 1 Think: 15% = 10% + 5% % of $22 = $2.20Move the decimal point one place left.Step 2 Think 5% = 10% ÷ 2 $2.20 ÷ 2 = $1.10Step 3 15% = 10% +5%= $ $1.10 = $3.30The tip should be about $3.30.
21 Check It Out! Example 3bEstimate the tax on shoes that cost $68.50 when the sales tax rate is 8.25%.Step 1 First round 8.25% to 8% and $68.50 to $70.Step 2 Think: 8% = 8(1%) 1% of $70 =$0.70Move the decimal point two places left.Step 3 8% = 8(1%)= 8($0.70) = $5.60The sales tax is about $5.60.
22 Lesson Quiz: Part 11. A computer salesperson earns a base salary of $32,000 per year plus a commission of 6% on total sales. Total sales for one year were $350,000. Find the salesperson’s total pay for the year.$53,0002. Find the simple interest paid for 9 months on a a $500 loan at 8% per year.$303. After 2 years the simple interest earned on an investment of 4000 was $216. Find the interest rate.2.7%
23 Lesson Quiz: Part 24. A family’s dinner check was $ Estimate a 15% tip.About $6.005.The sales tax rate is 7.1%. Estimate the sales tax on a television set that costs $399.About $28