## Math 6A, Lesson 9, Spring 2019, 4/21/2019

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1. Average Rate

Rate involves two quantities and it is usually expressed as one quantity per unit of another quantity.

\$/oz, mile/gal, words/min, \$/sq.ft, \$/hour

2. Speed, uniform/constant speed and average speed

Speed = (distance traveled) / (time taken)

Average Speed =  (Total distance traveled) / (total time taken)

3. Conversion of units

km/hr → m/s → miles/hr

\$/inch → \$/ft

\$/ticket → euro/ticket

4. Home Work:

• Handout:
• Three pages
• Workbook:
• Page 34: 5, 6, 7, 8, 9, 10
• Page 35: 11, 12, 13, 14, 15, 16, 17
• Page 36: 18, 19, 20, 21, 22

## Math 6A, Lesson 8, Spring 2019, 4/7/2019

zhenli Posted in Teaching Plan
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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