Presentation on theme: "Chapter 6 Lesson 7 Using Percent Equations Pgs"— Presentation transcript:
1 Chapter 6 Lesson 7 Using Percent Equations Pgs. 298-302 What you will learn:Solve percent problems using percent equationsSolve real-life problems involving discount and interest
2 VocabularyPercent Equation (298): an equivalent form of the percent proportion in which the percent is written as a decimalDiscount (299): the amount by which the regular price of an item is reducedSimple Interest (300): the amount of money paid or earned for the use of money
3 The Percent Equation Part = Percent <----The percent is Base written as a decimalPart Base = Percent Base Multiply each side byBase the basePart = Percent Base <-----this is the percent equation
4 Concept Summary: The Percent Equation TypeExampleEquationMissing PartWhat number is 75% of 4?n = 0.75(4)Missing Percent3 is what percent of 4?3 = n(4)Missing Base3 is 75% of what number?3 = 0.75n
5 Example 1: Find the Part Find 42% of 150 You know the base is 150 and the percent is 42%. Let n represent the part.n = 0.42(150) Write 42% as the decimal 0.42n = SimplifySo, 42% of 150 is 63. Is that reasonable? Yes becauseyou know that 75 is 50% of 150,so 42% should be less than half.
6 Example 2: Find the Percent 37.5 is what percent of 30?You know that the base is 30 and the part is Let n represent the percent.Part = Percent Base37.5 = n(30)37.5 = n(30) Divide each side by 301.25 = n Move the decimal 2 places left to change into a %So, 37.5 is 125% of 30
7 Example 3: Find the Base 83.5 is 125% of what number? You know that the part is 83.5 and the percentIs Let n represent the base.Part = Percent Base83.5 = 1.25nRemember, using the percent equation, thepercent is turned to a decimal.66.8 = nSo, 83.5 is 125% of 66.8
8 Example 4: Find Discount The percent equation can also be used to solve problems involving discount and interest.Example 4: Find DiscountA frozen pizza is on sale at a 25% discount. Find the sale price of the pizza if it normally sells for $4.85Method 1: First use the percent equation to find 25% of $4.85Let D = the discount Part = Percent BaseD = .25(4.85)D = Since this is money, round to the nearest hundredthD = 1.21Then find the sale price: $ $1.21 = $3.64
9 A frozen pizza is on sale at a 25% discount A frozen pizza is on sale at a 25% discount. Find the sale price of the pizza if it normally sells for $4.85Method 2: A discount of 25% means the item will cost 100% - 25% or 75% of the original price. Use the percent equation to find 75% of $4.85Let s represent the sale price.S = 0.75(4.85)S = Remember, dealing with $$ so round tonearest hundredth!The sale price of the pizza will be $3.64
10 Annual Interest Rate (as a decimal) Simple Interest Use the following formula: Interest------> I = prt <----- Time (in years) principal (amt. of $$ invested/ borrowed)
11 Example 5: Apply Simple Interest Formula I= prt What is the annual interest rate if $1600 is invested for 6 years and $456 in interest is earned?Fill in the formula!456 = 1600r6456 = 9600r9600R = Turn the decimal into a percentSo, the interest rate is 4.75%
12 Your Turn. Solve each problem using the percent equation Your Turn! Solve each problem using the percent equation. part = Percentbase12 is what percent of 400?What is 20% of 110?30 is 60% of what number?12= P400P= move the decimal to make it a %3%p = .20(110)p = 2230 = .60b50 = b
13 2 More!A jacket that normally sells for $180 is on sale at a 35% discount. What is the sale price of the jacket?How long will it take to earn $252 in interest if $2400 is invested at a 7% annual interest rate?D = .35(180)D = 63$180-$63 = $117I = prt252= 2400(.07)t252=168t1.5 = tIt will take 1.5 years
14 QUIZ TOMORROW over 6-6 and 6-7 Extra Practice by the door on your way out! Make sure you keep on top of this by reviewing everyday!