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Finding a Percent of a Number

Finding a Percent of a Number. 6.1.1.4 Determine equivalences among fractions, decimals and percents ; select among these representations to solve problems.

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Finding a Percent of a Number

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  1. Finding a Percent of a Number 6.1.1.4 Determine equivalences among fractions, decimals and percents; select among these representations to solve problems. 6.1.3.3 Calculate the percent of a number and determine what percent one number is of another number to solve problems in various contexts 6.1.3.4 Solve real world and mathematical problems requiring arithmetic with decimals, fractions, and mixed numbers

  2. I can… • Find the percent of a number • Calculate discount prices • Calculate sales tax Self Assessment 5- I can do it without help & teach others. 4- I can do this with no help, but I don’t know if I can explain it. 3- I can do this with a little help. 2- I can do this with a lot of help! 1- I don’t have a clue.

  3. Method 1: Using a fraction What is 75 % of 60? • Write and equation • Change the percent to a fraction • Simplify by cross canceling • Solve the equation 3 4 • 60 w = 15 60 1 3 4 To set up your proportion, think, “IS over OF equals PERCENT over 100.” = 45 • 1

  4. Method 1: Using a fraction What is 10 % of 36? • Write and equation • Change the percent to a fraction • Simplify by cross canceling • Solve the equation 10 100 • 36 w = 9 2 = 18 5 36 1 10 100 To set up your proportion, think, “IS over OF equals PERCENT over 100.” • 25 5 = 3.6

  5. Your Turn What is 85 % of 160? • Write and equation • Change the percent to a fraction • Simplify by cross canceling • Solve the equation 85 100 • 160 w = 8 16 17 85 100 = 136 To set up your proportion, think, “IS over OF equals PERCENT over 100.” 160 1 • 10 5 1

  6. Method 2: Using a decimal What is 10 % of 74? • Write and equation • Change the percent to a decimal • Solve the equation w = 0.1 • 74 = 7.4 To set up your proportion, think, “IS over OF equals PERCENT over 100.”

  7. Method 2: Using a decimal What is 20 % of 48? • Write and equation • Change the percent to a decimal • Solve the equation w = 0.20 • 48 = 9.6 To set up your proportion, think, “IS over OF equals PERCENT over 100.”

  8. Your Turn… What is 8 % of 90? • Write and equation • Change the percent to a decimal • Solve the equation w = 0.08 • 90 = 7.2 To set up your proportion, think, “IS over OF equals PERCENT over 100.”

  9. Finding a Discount The regular price of a pair of sneakers is $40. The sale price is 25% off the regular price. What is the sale price? • Find the discount • Subtract the discount from the regular price What is 25 % of $40? 5 25 100 2 40 4 To set up your proportion, think, “IS over OF equals PERCENT over 100.” w $10 • = 10 5 1

  10. Finding a Discount The regular price of a pair of sneakers is $40. The sale price is 25% off the regular price. What is the sale price? • Find the discount • Subtract the discount from the regular price What is 25 % of $40? To set up your proportion, think, “IS over OF equals PERCENT over 100.” 40 - 10 $30

  11. Finding a Discount The regular price of a sweatshirt is $15. The sale price is 30% off the regular price. What is the sale price? • Find the discount • Subtract the discount from the regular price What is 30 % of $15? To set up your proportion, think, “IS over OF equals PERCENT over 100.” w 15 • = 0.3 $4.50

  12. Finding a Discount The regular price of a pair of a sweatshirt is $15. The sale price is 30% off the regular price. What is the sale price? • Find the discount • Subtract the discount from the regular price What is 30 % of $15? To set up your proportion, think, “IS over OF equals PERCENT over 100.” 15.00 - 4.50 $10.50

  13. Your Turn… A store is having a 35% off sale on all items. An item is regularly priced at $49.50. What is the sale price? • Find the discount • Subtract the discount from the regular price What is 35 % of $49.50? To set up your proportion, think, “IS over OF equals PERCENT over 100.” w • = 0.35 49.50 17.325 Since it is $, round to the nearest cent $17.33

  14. Your Turn… A store is having a 35% off sale on all items. An item is regularly priced at $49.50. What is the sale price? • Find the discount • Subtract the discount from the regular price What is 30 % of $15? To set up your proportion, think, “IS over OF equals PERCENT over 100.” 49.50 - 17.33 $32.18

  15. Your Turn… Find the sale price of an item that is 22% off of $21.50. • Find the discount • Subtract the discount from the regular price What is 22 % of $21.50? To set up your proportion, think, “IS over OF equals PERCENT over 100.” w 21.50 • = 0.22 $4.73

  16. Your Turn… Find the sale price of an item that is 22% off of $21.50. • Find the discount • Subtract the discount from the regular price What is 22 % of $21.50? To set up your proportion, think, “IS over OF equals PERCENT over 100.” 21.50 - 4.73 $16.77

  17. Sales Tax is added to the purchase Finding Sales Tax You are buying dog food that costs $8.50. There is a 6% sales tax. What is the total amount of your purchase? • Find the sales tax • Add the sales tax to the regular price What is 6 % of $8.50? To set up your proportion, think, “IS over OF equals PERCENT over 100.” • 0.06 8.50 $0.51

  18. Sales Tax is added to the purchase Finding a Sales Tax You are buying dog food that costs $8.50. There is a 6% sales tax. What is the total amount of your purchase? • Find the sales tax • Add the sales tax to the regular price What is 6 % of $8.50? To set up your proportion, think, “IS over OF equals PERCENT over 100.” 8.50 + 0.51 $ 9.01

  19. Sales Tax is added to the purchase Finding Sales Tax The price of the cat toy is $9.50. Find the total cost with a sales tax of 8%. • Find the sales tax • Add the sales tax to the regular price What is 8 % of $9.50? To set up your proportion, think, “IS over OF equals PERCENT over 100.” • 0.08 9.50 $0.76

  20. Sales Tax is added to the purchase Finding a Sales Tax The price of the cat toy is $9.50. Find the total cost with a sales tax of 8%. • Find the sales tax • Add the sales tax to the regular price What is 8 % of $9.50? To set up your proportion, think, “IS over OF equals PERCENT over 100.” 9.50 + 0.76 $10.26

  21. Sales Tax is added to the purchase Your Turn… You are buying a pair of shoes that cost $28.80. There is a 5% sales tax. What is the total amount of your purchase? • Find the sales tax • Add the sales tax to the regular price What is 5 % of $28.80? To set up your proportion, think, “IS over OF equals PERCENT over 100.” • 0.05 28.80 $1.44

  22. Sales Tax is added to the purchase Your Turn… You are buying a pair of shoes that cost $28.80. There is a 5% sales tax. What is the total amount of your purchase? • Find the sales tax • Add the sales tax to the regular price What is 5 % of $28.80? To set up your proportion, think, “IS over OF equals PERCENT over 100.” 28.80 + 1.44 $ 30.24

  23. I can… • Find the percent of a number • Calculate discount prices • Calculate sales tax Self Assessment 5- I can do it without help & teach others. 4- I can do this with no help, but I don’t know if I can explain it. 3- I can do this with a little help. 2- I can do this with a lot of help! 1- I don’t have a clue.

  24. 8.7 Notes Percent of a Number • Write and equation • Change the percent to a fraction or decimal • Solve the equation Finding Discounts Find the discount Subtract the discount from the regular price Finding Sales Tax Find the sales tax Add the sales tax to the regular price

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