1. Calculating Rates

2. Speeds Speeds are often described as rates. Ex: MPH = miles per hour MPS = meters per second In all the following slides we will use d for distance, t for time and r for rate.

3. How far? If you traveled at 30 MPH for 3 hours, how far would you go? If you traveled for 10 hours at 60 MPH, how far would you go? What operation did you use to figure the distance?

4. Formula (or an equation) If 90 miles = 30MPH * 3 hours And 600 miles = 10 hours * 60 MPH Then Distance = rate * time or D = rt

5. Finding Rate If you go 60 miles in one hour, what is your rate? If you go 60 miles in 2 hours, what is your rate?

6. Formula for Rate If 60 MPH = 60 miles/ 1 hour and 30 MPH = 60 miles/ 2 hours 30 MPH = 60 miles/ 2 hours What is a formula for figuring rate? r = d/t rate = distance divided by time

7. Formula for time How long will it take you to go 90 miles at 30 MPH? How long will it take to go 600 mile at 60 MPH? Which operation did you use?

8. Formula for Time 3 hrs = 90 miles divided by 30 MPH 10 hrs = 600 miles divided by 60 MPH Time = Distance / rate t = d/r

9. Which is the faster rate? 35 miles in 15 minutes Or 76 miles in 30 minutes r=d/t r=d/t r=35/15 r=2.3 mph r=d/t r=76/30 r=2.5 mph

10. Which is farther? d = rt 17 mph for 17 minutes Or 11 mph for 22 minutes d = rt d = 17(17) d = 289 miles Or d = rt d = 11 * 22 d = 242 miles

11. Which takes longest? t=d/r Go 40 miles at 22MPH Or Go 60 miles at 28 mph t =d/r t =40/22 t =1.8 hours t =d/r t =60/28 t = 2.1 hours