SOLUTION: Jennifer drives to her friends house 20km away. There is no direct route so she travels 15km through the city at 50km/h and 15km on the highway at 100km/h. The trip takes 27minutes

Algebra ->  Customizable Word Problem Solvers  -> Travel -> SOLUTION: Jennifer drives to her friends house 20km away. There is no direct route so she travels 15km through the city at 50km/h and 15km on the highway at 100km/h. The trip takes 27minutes      Log On

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Question 647797: Jennifer drives to her friends house 20km away. There is no direct route so she travels 15km through the city at 50km/h and 15km on the highway at 100km/h. The trip takes 27minutes. Find Jennifer's average speed.
Answer by Alan3354(69443) About Me  (Show Source):
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Jennifer drives to her friends house 20km away. There is no direct route so she travels 15km through the city at 50km/h and 15km on the highway at 100km/h. The trip takes 27minutes. Find Jennifer's average speed.
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Avg speed = 2*50*100/(50+100)
= 200/3 km/hr
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Or, she went 30 km in 27 minutes
r = d/t = 30/27 km/min
= 200/3 km/hr