8:00 GED Math 4/19

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Introduction to Percent

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8:00 GED Math 4/19

  1. 1. • 1. Review: Ratio/Proportion• 2. Discuss Ratio/Proportion Quiz• 3. Introduction to Percent – The Basics• 4. The Percent Statement• NO CLASS MONDAY
  2. 2. • Percent means “out of 100” 400 400• So, if you get 4 out of 5 questions right on a quiz, we generally give a You can see these two fractions percent to show a grade. are equal, by multiplying diagonally.• Percentage is a way of putting numbers in the same terms so no matter Because of this relationship, you what you compare, an can set up a proportion to understanding can me calculate percentage, find the made. part, or find the whole.
  3. 3. • You will need to know how to convert: –A decimal to a fraction (place value) –A fraction to a decimal (division) –A fraction to a percent (division) –A percent to a fraction or decimal (place value/division)
  4. 4. • 1. Drop the percent sign (%). .45.% . Percent Decimal 45% 0.45 8% 0.08 37 ½ % 0.37 ½ or 0.375• 2. Move the decimal 250% 2.5 point two places to the LEFT.
  5. 5. • Change 35 % to a• 1. Drop the % fraction. sign.• 2. Write 100 as • the denominator.• 3. Reduce. • Common denominator =5
  6. 6. • 1. Drop the % sign. • Change 16 2/3 % to a fraction.• 2. Change to an improper fraction. %• 3. Multiply by 1• 4. Reduce. 2
  7. 7. Percent Part 15% of $25 is $3.75 Whole Part Whole $3.75 is 15% of $25 PercentYou will be asked to find the part, the percent, or the whole.
  8. 8. • Two Strategies:• 1. Turn the percent into a decimal and then multiply.• Ex) Find 25% of 12.• .25 x 12 = 3• 3 is 25 % of 12.
  9. 9. This relationship is ALWAYS TRUE. Step 1: Write aJosh got 4 out of 5 proportion statement.questions right on atest. What is hispercentage? Step 2: Find the cross Step 3: Divide by 5 products. on both sides.4 is the part.5 is the whole.We are looking forthe %.
  10. 10. • Find 25% of 12.•Step 1: Set up aproportion.•Step 2: Cross multiply.•Step 3: Divide
  11. 11. • Option 1: Change the percent to a decimal, then multiply.
  12. 12. • Option 2: Write a proportion statement.
  13. 13. • A state official predicts that 70% of the registered voters in Montana will vote on election day. If there are 514,000 registered voters in Montana, how many are predicted to vote?Step 1: Understand thequestion. “How manyregistered voters arepredicted to vote?”Step 2: What info doyou need? Use the % ofvoters predicted to voteand the number ofregistered voters.Step 3: Choose theoperation. What is 70%of 514,000?
  14. 14. • 6. Randi’s property tax bill is increasing by 3% this coming year. She now pays $890 a year in property tax.• A) By how much is her property tax going to increase?
  15. 15. • 6. Randi’s property tax bill is increasing by 3% this coming year. She now pays $890 a year in property tax.• B) How much will she pay next year?
  16. 16. • 1. First make a • 27 is what percent fraction. Put the of 45? part (is) over the whole (of) and reduce.• 2. Change the fraction to a percent.
  17. 17. • Use the calculator to find what percent 27 is of 45.1. Press AC2. Press 2 7 ÷ 4 5 SHIFT % The display should read 60. The answer is 60%.
  18. 18. • 1. 9 is what percent of • 7. The Melino family 36? was on vacation for 12 days. It rained 3 of those days. On what percent of their• 7 is what percent of 35? vacation days did it rain?
  19. 19. • 1. Change the • 20% of what is 9? percent to either a fraction or a decimal.• 2. Divide the number by that fraction or decimal.
  20. 20. • Use the calculator to find 20% of what number is 9.1. Press AC2. Press 9 ÷ 2 0 SHIFT % The display should read 45.
  21. 21. • 1. 18 is 50% of what • 6. Paul and Jane number? Bidwell pay $150 a month on their car loan. This is 5% of their monthly• 25% of what income. How much number is 30? do they make each month?
  22. 22. •P stands for the Part •% stands for the Percent P •W stands for the WHOLE •The line means by.% x W •The X means multiplied by
  23. 23. To Use the Percent P Circle: 1. Cover the symbol of the number you are looking for.% x W 2. Do the math shown by the uncovered symbols.
  24. 24. What is 50% of 8? P% x W
  25. 25. 4 is 50% of what number? P% x W
  26. 26. • To find a percent of a • What is 62 ½ % of 56? number: • Decimal• Step 1: Change the • 62.5 x 56 = 3500 percent to a decimal or a fraction. • Move decimal two places to the left.• Step 2: Multiply • 62 ½ % of 56 is 35.
  27. 27. • To find a percent of a • What is 62 ½ % of 56? number: • Fraction• Step 1: Change the percent to a decimal or a fraction.• Step 2: Multiply
  28. 28. • To find the part: • 27 is what percent of• 1. First make a fraction. 45? Put the part over the whole and reduce.• 2. Change the fraction to a percent.
  29. 29. • The Melino family was • Write the fraction as on vacation for 12 days. It rained 3 of those days. On what percent of their vacation did it • Change the fraction to rain? percent. •
  30. 30. • 1. Change the percent • 20% of what number is to either a fraction or a 9? decimal. • Change to a fraction• 2. Divide the number by that fraction or decimal.
  31. 31. Percent Part15% of $25 is $3.75 Whole Part Whole$3.75 is 15% of $25 Percent
  32. 32. • Mrs. Jackson makes $450 is her total income. a week. She pays $90 a week for She spends $90 on food. food. Money spent for food is what $90 is what percent of $450? percent of her income?
  33. 33. • 60% of what number is 45?• Lois got a 6% commission for selling a house. She sold a house for $120,000. Find the commission.
  34. 34. •P stands for the Part •% stands for the Percent P •W stands for the WHOLE •The line means by.% x W •The X means multiplied by
  35. 35. To Use the Percent P Circle: 1. Cover the symbol of the number you are looking for.% x W 2. Do the math shown by the uncovered symbols.
  36. 36. What is 50% of 8? P% x W
  37. 37. 4 is 50% of what number? P% x W
  38. 38. • Sally wants a new computer that costs $900. She has saved 75% of the price. How much has she saved? I am looking for the part. P %xW .75 x $900 = $675
  39. 39. • Bill paid $2 sales tax on a $40 shirt. The tax was what percent of the list price? I am looking for the percent. P %xW 2/40= 1/20=.05 5%

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