Math 6A, Lesson 8, Spring 2018, 4/1/2018

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1. Ratio

  • Meaning of ratio – Given any two similar quantities, a and b, the ratio of a to b (denoted by a:b) is defined as a:b = a/b, where b != 0
  • The quantities have to have same/similar unit.
  • Simplification of ratios: a:b = (ma): (mb) =  (a/m): (b/m), where m !=0

2. Ratios of three quantities: the ratio involving three quantities cannot be written as a fraction. However, it can be simplified by multiplying or dividing each term by the same constant.  For example, a:b = 5:6, b:c = 8:11, find a:b:c. Recall LCM, we convert each ratio to an equivalent ratio where the new value of b is the LCM of the original values of b:

a:b = 5:6 = 5*4 : 6*4 = 20:24

b:c = 8:11 = 8*3 :11*3 = 24:33

hence , a:b:c = 20:24:33

3. Word problems involving ratios

4. Home Work:

  • Handout:
    • two page
  • Page 33:
    • 1, 2, 3, 4
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