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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%.40.4 7%.07
Place the percent in a fraction with a denominator of 100. Simplify the fraction. Writing Percents as Fractions 26% 26 100 13 50 75% 75 100 3 4
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%.12512.5%.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 6 25 0.2424%
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? = 20 100 part whole 30 x = 100x 30(20) = 100x 600 100 = 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% = 0.18 0.18 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
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