A car made a 60 mile trip at an average speed of 20 mph. On the return trip, the car’s average speed was 30 mph. What was the average speed of the car for the entire two-way trip?
Q. A car made a 60 mile trip at an average speed of 20 mph. On the return trip, the car’s average speed was 30 mph. What was the average speed of the car for the entire two-way trip?
Calculate time to destination: Calculate the time taken for the trip to the destination.We know the distance to the destination is 60 miles and the average speed going there is 20 mph. To find the time, we use the formula time=speeddistance.Time to destination = 20 mph60 miles=3 hours.
Calculate time for return trip: Calculate the time taken for the return trip.The distance for the return trip is the same, 60 miles, but the average speed on the return trip is 30 mph. Again, we use the formula time=speeddistance.Time for return trip = 30 mph60 miles=2 hours.
Calculate total time for two-way trip: Calculate the total time for the entire two-way trip.Total time =Time to destination+Time for return tripTotal time =3 hours+2 hours=5 hours.
Calculate total distance for two-way trip: Calculate the total distance for the entire two-way trip.Total distance =Distance to destination+Distance for return tripTotal distance =60 miles+60 miles=120 miles.
Calculate average speed for two-way trip: Calculate the average speed for the entire two-way trip.The average speed is the total distance divided by the total time. We use the formula average speed =total timetotal distance.Average speed =5hours120miles=24mph.
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