Percent, 11.1

• A percent is the ratio of some number to 100.
• Percents are useful in making comparisons.
• Three procedures:
  • To change a decimal number to a percent:
    • Multiply by 100
    • Add a % sign.
  • To change a Fraction to a percent:
    • Divide the numerator by the denominator to obtain a decimal number
    • Follow the previous instructions.
  • To change a Percent to a decimal number
    • Remove the % sign.
    • Divide the number by 100.
• Percent change:
  • (new number - old number)/ old number X 100 %
  • If this is negative, it is a percent decrease.
  • If it is positive, it is a percent increase.
• Other Percent problems:
  part/whole x 100% = percent
• Example problems: Page 607, 7, 9, 12, 13, 15, 19, 25, 29, 33, 41