SOLUTION: 8. You jog at 9.1 km/h for 5.0 km, then you jump into a car and drive an additional 13 km. With what average speed must you drive your car if your average speed for the entire 18 k
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Question 1186711: 8. You jog at 9.1 km/h for 5.0 km, then you jump into a car and drive an additional 13 km. With what average speed must you drive your car if your average speed for the entire 18 km is to be 25 km/h? Found 2 solutions by Alan3354, ankor@dixie-net.com:Answer by Alan3354(69443) (Show Source):
You can put this solution on YOUR website! You jog at 9.1 km/h for 5.0 km, then you jump into a car and drive an additional 13 km. With what average speed must you drive your car if your average speed for the entire 18 km is to be 25 km/h?
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5 km at 9.1 km/hr takes 5/9.1 hours.
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18 km (5+13) at 25 km/hr takes 18/25 hours.
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5/9.1 = ~ 0.54945 hours
18/25 = 0.72 hours
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0.72 - 0.54945 = 0.17055 hours to travel 13 km.
13/0.17055 = ~76.22 km/hr
You can put this solution on YOUR website! 8. You jog at 9.1 km/h for 5.0 km, then you jump into a car and drive an additional 13 km.
With what average speed must you drive your car if your average speed for the entire 18 km is to be 25 km/h?
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let s = average speed in the car
:
Write a time equation, time = dist/speed
bike time + car time = total time + = + = .72
multiply by 9.1s, cancel denominators
5s + 9.1(13) = 9.1s(.72)
5s + 118.43 = 6.552s
118.43 = 6.552s - 5s
118.43 = 1.552s
s = 118.43/1.552
s = 76.3 km/hr
