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# help

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Bill made a trip to the train station and back. The trip there took six hours and the trip back took four hours. He averaged 45 km/h on the return trip. Find the average speed of the trip there.

Mar 21, 2020

#1
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Let's first start off with a knowledge of what "average speed" actually is. Average speed is defined as:

total distance / total time

The distance to the train station is equal to 45 * 4km, which is how far he traveled on the return trip(45 km per hour for 4 hours). That means that the distance for one trip is equal to 180 km. Since we only need total distance / total time, the total distance is equal to the distance of one trip multiplied by 2, which is 180*2 = 360. Then, total time is just 6 hours + 4 hours, which is 10 hours.

360 / (6+4) = 360 / 10 = 36 km/h

Mar 21, 2020
#2
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Nice, jfan17!

Here's another way to put it:

Since we know that Bill traveled 4 hours, we can do 45*4 which would be 180 for one trip.

We need to find out the (total distance)/(total time).

The total distance, or round trip is just multiplying one trip by 2. That will get us 180*2 = 360.

The total time, as we know, is 10 hours.

From now it is easy: 360/10=36

Bill traveled with an average speed of 36km/h on the way there.

Hope this helped!

Mar 21, 2020
#3
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Trip back was  4 hours  x  45 m/hr = 180 miles

Trip To took 6 hours     180 miles/6 hours = 30 m/hr  for the trip there

Mar 21, 2020