SOLUTION: rudy drives for an hour at 80 km/h, then 40 km/h for two hours. what was his average speed?

Question 828673: rudy drives for an hour at 80 km/h, then 40 km/h for two hours. what was his average speed?

Answer by TimothyLamb(4379) (Show Source): You can put this solution on YOUR website!
---
s = d/t
t = d/s
d = s*t
---
1st leg:
d = 80*1 = 80 km
---
2nd leg:
d = 40*2 = 80 km
---
total distance:
160 km
total time:
3 hr
---
answer:
average speed:
s = 160/3
s = 53.3 km/hr
---
NOTE:
average speed is NOT:
(80 km/h + 40 km/h)/2 = 60 km/h
---
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