1. Slope as Rate of Change

2. Calculating a rate of change. Dependent variable is the y variable. Usually on the bottom. Independent variable is the x variable. Usually on the top. y x

3. If gasoline is left in an open container, it evaporates. The table below shows how many gallons of gas evaporate over time. Find the number of gallons that evaporate per hour.

4. If gasoline is left in an open container, it evaporates. The table below shows how many gallons of gas evaporates over time. Find the number of gallons that evaporate per hour. 9 4

5. 9 4 = 9 4 =9 ÷4 = 2.25 gallons per hour

6. Press Pause and take turns trying a problem. One of you try the first, the next person try the next, etc. If there are more problems than people, then keep taking turns. When you’re done, press play for the answers. 1. Calculate the miles per gallon Gallons5101520 Miles75150225300 2. Calculate the cost per hour Hours2468 Cost$1.50$3.00$4.50$6.00 3. Calculate the miles per hour Hours3183348 Miles754508251200 4. Calculate the pay per hour Hours57911 Pay $26.25$36.75$47.25$57.75 5. Calculate the people per square ft Sq. Ft26810 People391215 6. Calculate the cost per minute Minutes100200300400 Cost$7$14$21$28

7. Answers. Press Pause at the end until you’re done checking. 1. Calculate the miles per gallon Gallons5101520 Miles75150225300 2. Calculate the cost per hour Hours2468 Cost$1.50$3.00$4.50$6.00 3. Calculate the miles per hour Hours3183348 Miles754508251200 4. Calculate the pay per hour Hours57911 Pay $26.25$36.75$47.25$57.75 5. Calculate the people per square ft Sq. Ft26810 People391215 6. Calculate the cost per minute Minutes100200300400 Cost$7$14$21$28

8. Try these two on your own. They are in your packet. This table describes the amount spent on magazine subscriptions per year. Find the rate of change. This table describes the number of buses added per year. Find the rate of change. Year20012002200320042005 Amount spent$127$134$141$148$155 Year19801985199019952000 Number of buses 823832841850859