SOLUTION: A professor drove from Denver to Boulder during rush hour at an average speed of 30 miles per hour, and then drove back the same way at an average speed of 45 miles per hour. If

Question 672892: A professor drove from Denver to Boulder during rush hour at an average speed of 30 miles per hour, and then drove back the same way at an average speed of 45 miles per hour.
If the round trip took 1 hour and 45 minutes, how many miles is the professor's one-way trip from Denver to Boulder?
If the answer is not an integer, enter it as an exact decimal.
____________miles

Answer by ankor@dixie-net.com(22740) (Show Source): You can put this solution on YOUR website!
A professor drove from Denver to Boulder during rush hour at an average speed of
30 miles per hour, and then drove back the same way at an average speed of 45 miles per hour.
If the round trip took 1 hour and 45 minutes, how many miles is the professor's
one-way trip from Denver to Boulder?
:
let d = the distance of the one-way trip
:
Write a time equation: time = dist/speed. Change 1 hr 45 min to 1.75 hrs
:
to time + return time = total time
+ = 1.75
multiply by the LCM of 30 and 45, that's 90, resulting in:
3d + 2d = 90(1.75)
5d = 157.5
d = 157.5/5
d = 31.5 miles
:
:
Check this, find the time each way
31.5/30 = 1.05 hrs
31.5/45 = 0.70 hrs
-----------------
total time: 1.75 hrs

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