Solving Percent Problems Mrs. Maher

Rate and Ratio Review Ratios (4 forms of a ratio) 1) 5 flutes to 2 guitars 2) Of the students got an A. 3) 3 boys : 2 girls 4) 4 out of 5 students had their homeworkRates (simplify so that you get “per” unit) 1)6 gallons for $6.75 $1.13 per gallon 2)Sold 120 rings in 8 h 15 per hour 3)Drove 50 miles in 2 hours 25 miles per hour

Solving a Proportion b = 1 Solve using equivalent fractions x4 6 x 12 = 8r 72 = 8r 72 / 8 = r 9 = r Solve using cross products

Finding Percent of a Number Solve using fractions Solve using decimals Find 50% of 25 Find 35% of x 70 = 24.5

Percent of a Number (using a proportion to solve) We can use proportions to solve all percent problems. So when we don’t know the “of” or the “%” we can use a proportion to solve.

Percent of a Number: Solve for “is” What is 16% of 50?What is 16% of 50? You could change the percent to a decimal or fraction and multiply. OR You could set up a proportion and use cross products or equivalent fractions to solve:

Percent of a Number: solve for “is” 1) What is 24% of 50? 2 2 X = 12 Check: Use Cross products!! Solve using equivalent fractions (or cross products)

Percent of a Number Finding the “of”Finding the “of” Do the same thing, but solve for “of”. 90 is 75% of what number?90 is 75% of what number? Use Cross Products to solve, then check. X = 120

Percent of a Number: Solving for the % What if you don’t know the percent? Well, you can use the same proportion, but solve for the percent. 17 is what percent of 20?17 is what percent of 20?

Percent of a Number Find the percent. 1)21 is what percent of 30? 2)On a 50 point quiz, you received 48 points. What percent did you receive? 3) On a 40 point quiz, you received 38 points plus 6 bonus points. What is the percent?