Question 560495
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a.  Let *[tex \Large t] represent time for the entire trip.  Then *[tex \Large \frac{t}{2}] represents the amount of time at 56 km/h.  And *[tex \Large \frac{t}{2}] also represents the amount of time at 70 km/h.  Distance equals rate times time, so the distance traveled at 56 km/h is *[tex \LARGE 28t].  The distance traveled at 70 km/h is *[tex \LARGE 35t].  The sum of these distances is the total distance, *[tex \Large d], from Lafayette to Houston, so


*[tex \LARGE \ \ \ \ \ \ \ \ \ \ 28t\ +\ 35t\ =\ d]


*[tex \LARGE \ \ \ \ \ \ \ \ \ \ \frac{d}{t}\ =\ 63]


Since distance equals rate times time, rate equals distance divided by time.  Hence the average speed from L to H is 63 km/h.


Write back and I'll give you a quote to do the rest of this.


John
*[tex \LARGE e^{i\pi} + 1 = 0]
My calculator said it, I believe it, that settles it
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