1. Chapter 2 Unit Question How do we use the basic operations in Algebra?

2. Open Learning Logs Date on Left…Section 2 – 5 on right

3. Warm Up Think about how long it takes you to take a shower. With that in mind, calculate how many showers you could take in 24 hours.

4. Section 5 How do we multiply and divide rates?

5. Homework Check

6. Rate Factor Model for Multiplication When a rate r is multiplied by another quantity x then the product is r x (or rx) The UNIT of the product rx is the product of the units of r and x. NOTE: This lesson is NOT about numbers, it’s about the UNITS!

7. = 175 minutes Example It takes Barb 25 minutes to walk 1 mile. At this rate, how long would it take her to walk 7 miles? Ask yourself, “What units answer the question?” 25 minutes 1 mile 7 miles = 175 minutes The unit miles cancels out just like variables in fractions! We need that unit in the numerator!

8. 15 Gallons Example…Weird Suppose Gas costs $3.75 a gallon at Sheetz and I bought $56.25 worth of gas. How many gallons did I buy?… $3.75 1 gallon $3.75 Reciprocate! HoffmaClue: Reciprocal Rates! $56.25 1 =15 Gallons Ask yourself, “What units answer the question?” But We need GALLONS in the numerator!

9. Example The scoring record in the NBA is 50.4 pts/game by Wilt Chamberlain in 1962. On the average, how many points did he score per minute? (NBA game is 48 minutes) Ask yourself, “What units answer the question? 50.4 points 1 game 48 minutes 1 game Is there a problem here? points minute Is our final answer unit What should we do? 1 game 48 minutes = 50.4 points 48 minutes = 1.05 pts/min

10. Definition If a and b are quantities with different units, then is the amount of quantity a per quantity b. As we last discussed rates, the UNITS are the important thing here!

11. Find the temperature change!!! The temperature rises 35  in 5 hours The temperature drops 42  in 6 hours 35  5 hours = 7  1 hour Or…a RISE of 7° PER hour -42  6 hours = -7  1 hour Or…a DROP of 7° PER hour NOTE: Rise = positive Drop = Negative

12. Try this… Alice reads 140 pages per day. At this rate, how long would it take her to read a book that is 630 pages long? It takes Alice 4½ days to read the book

13. Homework HoffmaSheet 2 – 5