SOLUTION: While driving on the highway, Dave averages 60 miles per hour. In the city, he averages 30 miles per hour. On a trip to his grandmother's house, Dave drove 235 hours on the highway

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Question 843865: While driving on the highway, Dave averages 60 miles per hour. In the city, he averages 30 miles per hour. On a trip to his grandmother's house, Dave drove 235 hours on the highway and 115 hours in the city. What was Dave's average speed for the entire trip, in miles per hour? Round to the nearest tenth.
Found 2 solutions by josgarithmetic, lwsshak3:
Answer by josgarithmetic(39621) About Me  (Show Source):
You can put this solution on YOUR website!
_______________speed__________time_____________distance
Highway________60_____________235______________
City___________30_____________115______________


What was average speed for the whole trip?
R*T=D, uniform rate equation for travel.

_______________speed__________time_____________distance(MILES)
Highway________60_____________235______________60%2A235
City___________30_____________115______________30%2A115
TOTALS________________________350______________17550

Using the totals obtained, the average speed was 17550%2F350=highlight%28highlight%2850.1%29%29 miles per hour

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That would be an incredible drive to take to visit his mother. That 17550 miles trip is about 7%2F10 the distance around the earth! All that using just "highway" and "city" driving?

Answer by lwsshak3(11628) About Me  (Show Source):
You can put this solution on YOUR website!
While driving on the highway, Dave averages 60 miles per hour. In the city, he averages 30 miles per hour. On a trip to his grandmother's house, Dave drove 235 hours on the highway and 115 hours in the city. What was Dave's average speed for the entire trip, in miles per hour? Round to the nearest tenth.
***
distance traveled on the highway=235*60=14100 miles
distance traveled 1n the city=115*30=3450 miles
total distance traveled=14100+3450=17550 miles
total travel time=235+115=350 hrs
Dave's average speed=distance/travel time=17550/350=50.1 miles per hour