SOLVING PERCENTAGE of CHANGE EQUATIONS PRE213 A dress costs $45 but there’s a 25% off sale. What’s the new price? Sometimes it helps to use a table to organize information. PercentReal 100% Change (+/–) New Original STEP 1: set up the table. NEVER CHANGES
SOLVING PERCENTAGE of CHANGE EQUATIONS PRE213 A city’s population increases 12% from 1990 to The population was 125,000 in What was the new population? PercentReal 100%125, % Change (+/–) New Original STEP 2: fill out table.
SOLVING PERCENTAGE of CHANGE EQUATIONS PRE213 A city’s population increases 12% from 1990 to The population was 125,000 in What was the new population? PercentReal 100%125, % 112%X Change (+/–) New Original STEP 3: fill in missing pieces. We’re asked to find the new population.
SOLVING PERCENTAGE of CHANGE EQUATIONS PRE213 A city’s population increases 12% from 1990 to The population was 125,000 in What was the new population? Change (+/–) New Original STEP 4: set up a proportion. PercentReal 100%125, % 112%X ,000 x =
SOLVING PERCENTAGE of CHANGE EQUATIONS PRE213 A city’s population increases 12% from 1990 to The population was 125,000 in What was the new population? STEP 4: solve the proportion ,000 x = 112(125,000) = 100x 14,000,000 = 100x 140,000 = x The new population was 140,000!
SOLVING PERCENTAGE of CHANGE EQUATIONS PRE213 A dress costs $45 but there’s a 25% off sale. What’s the new price? PercentReal 100% Change (+/–) New Original Answer on next slide.
SOLVING PERCENTAGE of CHANGE EQUATIONS PRE213 A dress costs $45 but there’s a 25% off sale. What’s the new price? PercentReal 100%$45 -25% 75%X Change (+/–) New Original x = 75(45) = 100x 3375 = 100x $33.75 = x The new price is $33.75!