Question 1017825
Your friend drives 60km with an avg speed of 30km/h. How fast must she drive back, the same 60km, to avg 60km/h over the entire trip of 120km?
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This is a "trick question."
She has to make the return in zero time.
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60 km/30 km/hr = 2 hours
120 km/60 km/hr = 2 hours
Time is up when she starts back.