Percents and Proportions - Henrico County Public Schools百分数与比例-亨利科县公立学校.pptVIP

Percents and Proportions Setup of a Percent Proportion Is = part Of = whole Example In Arkansas, the state sales tax is 4.5%. You want to buy a $195 bicycle in Arkansas. How much is the tax? Example In Arkansas, the state sales tax is 4.5%. You want to buy a $195 bicycle in Arkansas. How much is the tax? $8.78 Example Suppose 11,550 elementary students make up 14% of a city’s population. What is the population of the city? Example Suppose 11,550 elementary students make up 14% of a city’s population. What is the population of the city? 82,500 Example Write a proportion to solve each problem. C) Find 12.5% of 90 D) Find 5.75% of 1000 Example Write a proportion to solve each problem. A) Find 25% of 120 B) Find 85% of 150 Your Turn A) 10 is 25% of what number? B) 36 is 75% of what number? Practice Problem What percent of 60 is 15? What are we looking for? What is the base? What is the part? How do we set up the proportion? percent 60, remember “of” 15, remember “is” Solve Step 1: Cross multiply 15 x 100 = 60 x p Step 2. Simplify 1500 = 60p Step 3. Solve for p 1500/60 = p 15 is 25% of 60 P= 25% Your turn What percent of 25 is 30? Remember: Identify base, part What is the unknown How do we set it up? Your turn answer 120% Practice problems 1) What number is 40% of 80? 2) 75 is 20% of what number? 3) What percent is 45 of 60? Remember: identify what you know, what you are solving for, set up proportion and solve. Practice problems answers 32 375 75% * * * * * * * * * * * * * * * * * * * * * * * * * * * *