Hi, there--
THE PROBLEM--
You are traveling in a train. The train has traveled 45 miles from the last stop in 36 minutes.
What is the average speed of the train?
A SOLUTION--
The definition of average speed is total distance traveled (on average) in a given interval of
time. Average speed is the speed the train would have gone if it traveled at exactly the same
speed throughout its journey. Typically, we would give the average speed of a train in distance
per hour.
We know that the train traveled 45 miles in 36 minutes. We can find how many miles the train
travelled (on average) in each 1-minute interval by dividing the 45 miles into 36 equal
1-minute pieces. We see that 45/36=1.25. On average, the train traveled 1.25 miles for each
one-minute interval.
If we want to know the average speed in miles per hour, we multiply by 60 because there are
60 one-minute pieces in each hour. We see that 60*1.25=75. So, on average, the traveled at a
speed of 75 miles per hour.
That's it.
Mrs. Figgy
