Math 6A, Lesson 6, Spring 2017, 3/25/2017

1. Quiz: simplify algebraic expression and solve word problems using equations

2. 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
• 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

• Word problems involving ratios

3. Home Work:

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