Percents, Fractions, and Decimals Finding a Percent of a Number Lessons 6.6 & 6.7

  Find a percent of a quantity as a rate per 100 (e.g., 30% of a quantity means 30/100 times the quantity); solve problems involving finding the whole, given a part and the percent.  Use ratio and rate reasoning to solve real-world and mathematical problems CCS: 6.RP.3.

  Students will be able to:  Represent percents in different but related ways, such as a ratio, a fraction and a decimal  Use proportions to solve percentage problems  Use decimals to calculate daily transactions (finding sales tax or figuring tips on restaurant bills) Objectives

  A percent is a ratio that compares a number to 100. It means “per 100.”  49 out of 100 is 49%. Vocabulary

  Imagine a decimal point in the place of the percent sign, and move the decimal two spaces to the left (the same as dividing by 100). Writing Percents as Decimals 26%.26 40% %.07

  Place the percent in a fraction with a denominator of 100.  Simplify the fraction. Writing Percents as Fractions 26% %

  Move the decimal point two spaces to the right, and add a % symbol (this is the same as multiplying by 100). Writing Decimals as Percents.34 34%.19 19% %.6 60% 1 100%

  Divide the numerator by the denominator to get a decimal.  Change the decimal to a percent by moving the decimal point to the right (multiply by 100). Writing Fractions as Percents %

  Writing Percents as Fractions and Decimals Writing Percents as Fractions and Decimals Video Time

Should we use decimals OR proportions (fractions) OR both???

 Using a Proportion  Set up a proportion that uses the percent over 100.  Cross multiply to write an equation.  Solve the equation. To set up your proportion, think, “IS over OF equals PERCENT over 100.”

 Example – What is 20% of 30? = part whole 30 x = 100x 30(20) = 100x = x6

 Using a Decimal  Change the percent to a decimal.  Multiply that decimal by the number you are finding the percent of.

 Example – What is 18% of 70? 18% = x 70 = 12.6

  Finding Percents of a Number Finding Percents of a Number  Using Proportions to find Percents of a Number Using Proportions to find Percents of a Number Video Time!

 Homework Time! Reteaching 6.6 and 6.7 Handout Classwork Time! Math at the MallMath at the Mall -practice percentages and finding the best deal while shopping at a virtual mall