Math 009 Unit 5 Lesson 6

Obj: To solve equations involving percents Most percent problems that we will be working with can be written in the form: amount = percent  base This statement can be changed into the proportion amount = percent base 100

Obj: To solve equations involving percents Because most of the problems will be written in words, you need to get used to some of the terminology and what the words mean What is written as an unknown, (x) of indicates multiplication is is written as an equal sign

Obj: To solve equations involving percents Example: What is 4% of $85,000 x =4%  85,000 x = $3400 x 85,000 = x = 340,000 x = 340,000  100

Obj: To solve equations involving percents x = Example: What is 8.7% of x = 1392 x = 1392  100 x = 13.92

Obj: To solve equations involving percents Example: Find 15 % of 400 x = x = x = 6100 x = 6100  100

Obj: To solve equations involving percents Example: What is 16 % of 66 x = 1100  100 x = x 66 = x = 1100

Obj: To solve equations involving percents Remember what the following words mean in percent equations What is written as an unknown of indicates multiplication is is written as an equal sign what of is

Obj: To solve equations involving percents Example: 24 is what percent of =x %  60 x = x x = 2400 % = x = 2400  60

Obj: To solve equations involving percents Example: What percent of 40 is 30 ? 30=x%  40 x x = 3000 = x = 3000  40 x = 75 %

Obj: To solve application problems The monthly payment for the Kaminski family is $ What percent of the Kaminski’s monthly income of $3750 is the house payment ? Strategy: What percent of $3750 is $ ? Answer: House payment is 21% of the income x = 3750 x = 78,750 x = 78,750  3750 x = 21 x%  3750 =

Obj: To solve application problems On one Monday night, million of the approximately million households watching television were not watching David Letterman. What percent of the households were watching Letterman? Round to the nearest percent – = 9.37 million were watching x x  Answer: About 23% of the households were watching What percent of is 9.37 ? x%  = 9.37 = x = 937 x = 937  40.76

Obj: To solve equations involving percents Example: 18% of what is %= x  900 x = x 18 x = 90,000 = x = 90,000  18

Obj: To solve equations involving percents 15 is 2.5 % of what ? 2.5 x = 1500 x = = 2.5% x  = x = 1500  x

Obj: To solve application problems A used car has a value of $10,458 which is 42% of the car’s original value. What was the car’s original value ? Strategy: 10,458 is 42% of what ? 10,458 = 42%  x 42 x = 24,900 Answer: The original value is $24, x = 1,045,800 = x = 1,045,800  ,458 x

Obj: To solve application problems A store has a tennis racket on sale for $89.60 which is 80% of the original price. What is the dollar difference between the original price and the sale price ? Strategy: is 80% of what 2. subtract $89.60 from that answer x 100 x = $112 Answer: The difference is $ x = 8960 Original price = x = 8960  = 80%  x

Obj: To solve application problems A quality control inspector found that 1.2 % of 2500 telephones inspected were defective. How many telephones inspected were not defective. Strategy: 1. find the number of defective phones 2. subtract that number from 2500 Defective phones: What is 1.2% of 2500 Answer: 2470 phones were not defective x 2500 = x = 3000 x = 3000  100 x = 30

Obj: To solve application problems A worker’s hourly wage was $23.50 before an 8% raise. What is the new hourly wage? Strategy: 1. find 8% of $ add that amount to the original wage What is 8% of $23.50 x = 100x = 188 New wage = $25.38 x = 1.88 x = 188  100