SOLUTION: If you drove for 30 minutes at 60 mph and 10 minutes at 38 mph. What was your average speed for the trip?

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Question 711756: If you drove for 30 minutes at 60 mph and 10 minutes at 38 mph. What was your average speed for the trip?
Found 2 solutions by checkley79, Edwin McCravy:
Answer by checkley79(3341)   (Show Source): You can put this solution on YOUR website!
D=RT
D=60*.5
D=38*.167
D=60*5+38*.167
D=30+6.346
D=36.346 MILES.
36.346=R(.5+.167)
36.346=.667R
R=36.346/.667
R=54.34 MPH. IS THE AVERAGE SPEED.
Answer by Edwin McCravy(20056)   (Show Source): You can put this solution on YOUR website!
The other tutor used decimals and rounded off, making his answer off
a little.  I'll use fractions.

We use two formulas:

Distance = Rate × Time

Average Rate = Total Distance ÷ Total Time

When you went 30 minutes (half an hour) at 60 mph,
you went 60× = 30 miles  

When you went 10 minutes ( of an hour) at 38 mph,
you went 38× =  =   =  miles 

To find the total distance, we use the improper fraction for
the distance at 38 mph 

Total distance =  or  miles.

 Total time =  or  hr.

Average Rate = Total Distance ÷ Total Time

We will use the improper fraction for the total miles  

Average Rate = ÷mph.

Edwin
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