SOLUTION: A car complete 10 mile trip in 20 minutes.If car does 1/2 of trip at speed 20 miles/hr, What is the correct speed for remainder of distance?

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Question 1042398: A car complete 10 mile trip in 20 minutes.If car does 1/2 of trip at speed 20 miles/hr, What is the correct speed for remainder of distance?
Found 2 solutions by ankor@dixie-net.com, josgarithmetic:
Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
You can put this solution on YOUR website!
A car completes a 10 mile trip in 20 minutes.
If car does 1/2 of trip at speed 20 miles/hr,
At 20 mph he completes 5 mi in 15 min; (5/20 = .25 hrs which is 15 min)
therefore
he has to complete 5 mi in the remaining 5 min
What is the correct speed for remainder of distance?
speed = dist/time; 5 min = 1/12 hr
s = 5%2F%281%2F12%29
s = 5 * 12
s = 60 mph to complete 5 mi in 5 min
:
Check this, find the dist at each speed (dist = time * speed)
15 min: 1/4 * 20 = 5 mi
5 min: 1/12 * 60 = 5 mi
-----------------
total dist 10 mi

Answer by josgarithmetic(39617) About Me  (Show Source):
You can put this solution on YOUR website!
                    RATE            TIME           DISTANCE
FIRST HALF          20               x              20x
SECOND HALF         r                y               ry
Total                                1/3            10

Average Rate  10%2F%281%2F3%29=30%28miles%2Fhour%29 according to description

Also average rate is %2820%2Br%29%2F2=30. Solving here for r should be enough.

HALF the trip is 5 miles.
This system may be better:
system%2820x=5%2Cry=5%2Cx%2By=1%2F3%29
Remember, you mainly want a finished value for r.