Ratio and Proportion

• A ratio shows how an object’s quantity is related to another object’s quantity.
• Using Ratio to Compare a Part to a Whole

  <portion of the whole> : <total number portions of the whole>
• A proportion indicates that the two ratios are equal
• The proportion’s first and last terms are called the extremes
• the second and third terms are called the means.
• Fill in the blanks

  A) Means

  B) Extremes

  
• Properties of Proportion

  1. Product of means is equal to product of extremes
  2. Reciprocal of ratio in proportion are equal
  3. switching the means and extremes will result in proportion
• Solve: Suppose that on a specific date, 1 US dollar equals ₱50. How many US dollars is equivalent to ₱650?

  1:50 then N:650
• Leonor loves animals. He has a lot of dogs and cats in his house. The ratio of dogs to his cats is 1 : 3. The total number of dogs and cats is 8. How many cats does Leonor own?

  1 x N and 3 x N = 8

  4 x N = 8

  N=2

  Cats = 6
• When A is divided by 5, the result will equal the result when you divide B by 2. What is the result if you divide A by B?

  A : 5 = B : 2

  A : B = 5 : 2
• If 5 : 4 = 35 : 28, what should be N so that 4 : 5 = 28 : N

  N = 35