SOLUTION: Test prob: For 2 hours of a 400-mile trip, ave speed 40mph. Determine ave speed maintained for remainder of trip for ave speed of entire trip to be 50 mph. My figures: First par

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Question 499542: Test prob: For 2 hours of a 400-mile trip, ave speed 40mph. Determine ave speed maintained for remainder of trip for ave speed of entire trip to be 50 mph.
My figures: First part: 80m/2h=40mph
Second part: 320m/time(t)=ave mph (a)
Complete trip: 400m/(2+t)=50mph
I am at a loss. Can you please help me compute the average speed for the second part of the trip? Thank you for your help.

Answer by Alan3354(69443) About Me  (Show Source):
You can put this solution on YOUR website!
For 2 hours of a 400-mile trip, ave speed 40mph. Determine ave speed maintained for remainder of trip for ave speed of entire trip to be 50 mph.
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My figures: First part: 80m/2h=40mph
Second part: 320m/time(t)=ave mph (a)
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400/50 = 8 hours total time
80 miles traveled leaves 320 miles
2 hours used leaves 6 hours
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2nd part is 320 miles in 6 hours
r = 320/6 =~ 53.33 mi/hr