Ratio and Proportion

• Ratio


  The comparison between two numbers or quantities with the same units or the same category
• Ways to express a ratio

  • Column form
  • Division form
  • Phrase form
  • Fraction form
• Simplifying a ratio


  Divide the numerator and denominator by the greatest common factor
• Proportion


  An equation that shows two ratios are equal
• Identifying a proportion


  1. Check if the product of the means equals the product of the extremes

  2. Check if the ratios can be simplified to the same ratio
• The product of the extremes equals the product of the means in a proportion
• Extremes


  The two outer terms in a proportion
• Means


  The two inner terms in a proportion
• Multiplying the extremes and the means


  To determine if the ratios are proportional
• If the product of the extremes equals the product of the means, then the ratios are proportional
• Cross multiplication property: a/b = c/d, then ad = bc
• Sum of the original proportion: a/b = c/d, then (a+c)/(b+d) = a/b = c/d
• Solving proportions


  Cross multiply the extremes and means to find the missing value