Question 995930
How far can a man drive into a country if he drives out at 40 miles per hour, returns over the same road at 30 miles per hour, and spends 8 hours away from home, including a 1-hour stop for lunch?
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Avg speed of a round trip = 2*r1*r2/(r1 + r2)
= 2*40*30/(40+30) = 240/7 mi/hr
Driving for 7 hours --> RT distance = (240/7)*7 = 240 miles
--> 120 miles each way.