SOLUTION: A 555 mile, 5 hour plane trip was flown at two speeds. For the first part of the trip the average speed was 105 mph. Then the tailwind picked up, and the remainder of the trip wa

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Question 796916: A 555 mile, 5 hour plane trip was flown at two speeds. For the first part of the trip the average speed was 105 mph. Then the tailwind picked up, and the remainder of the trip was flown at an average speed of 115 mph. For how long did the plane fly at each speed?
Your help is appreciated. The formula give is d=rt but I cannot figure this one out. Do I need to get average mph for the entire trip first? Then what formula do I use?
Again, thanks for the help.
Answer by solver91311(24713) About Me  (Show Source):
You can put this solution on YOUR website!


Let represent the distance traveled at 105 mph. Then, since the entire trip was 555 miles, the distance traveled at 115 mph must be

Let represent the time spent at 105 mph. Then, since the entire trip took 5 hours, the time spent at 115 mph must be

The description of the portion of the trip at 105 mph based on distance equals rate times time is then:



Whereas the description of the rest of the trip is:



Substitute for :



Solve for , then calculate

John

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