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Lesson 4-3 Proportions and Percent Equations. Objective: To use proportions when solving percent problems and to write and solve percent problems. …and why?. One example of a real world connection is to calculate the total water supply of the USA. PERCENT REMINDER.
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Lesson 4-3Proportions andPercent Equations Objective: To use proportions when solving percent problems and to write and solve percent problems.
…and why? • One example of a real world connection is to calculate the total water supply of the USA.
PERCENT REMINDER • A percent is a ratio comparing a number to 100. • USE THE FOLLOWING PROPORTION FOR SOLVING PERCENT PROBLEMS: ‘ N* ‘= ‘ part ‘ 100 whole *N/100 is the percent.
Finding the percent. Ex. 1) What percent of 40 is 30? Finding the part. Ex. 2) Find 30% of 40. Examples 1 & 2, page 197
Example 3, page 198 • Ex. 3 – Charlie worked 31.5 hours at a hospital as a volunteer. This represents 87.5% of the school’s requirement for community service. How many hours does his school require for community service?
Percent Equations • Key Words • “What …” is the unknown. Use x. • “Is” means =. • “Of” means to multiply.
A) What is 85% of 320? B) 393 is 60% of what number? Ex. 4, page 198Write and solve a percent equation.
Ex. 5a) 105 is 125% of what number. Ex. 5b) What percent of 320 is 1.6? Ex. 5c) 640 is what percent of 32? Ex. 5d) 0.13% of what number is 3000? Example 5, page 199Find each number or percent.
Ex. 6a) 49% of 280 is what number? Ex. 6b) What is 65% of 334? Ex. 6c) What is 74.2% of 44? Ex. 6d) 11% of 521 is what number? Using Estimation, page 199Use fractions to estimate.
Example 7, page 200 A store advertises sneakers on sale for 33% off. The original price of sneakers is $56. • A) Estimate the amount the sneakers have been marked down. • B) Estimate the sale price of the sneakers.
SUMMARY TO SOLVE PERCENT PROBLEMS either • Use a percent proportion N/100 = part/whole Or • A percent equation where “is” means = and “of” means to multiply.
Assignment P. 200 1 – 57 odd; 61 – 73 odd