SOLUTION: Hello there, I've been trying to answer this question but I can't seem to arrive at the correct answer which is supposed to be 17 mph, any help would be much appreciated, thank

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Question 1178426: Hello there,
I've been trying to answer this question but I can't seem to arrive at the correct answer which is supposed to be 17 mph, any help would be much appreciated, thank you.
Two trains travel at right angles to each other after leaving the same train station at the same time. Two hours later they are 42.80 miles apart. If one travels 4 miles per hour slower than the other, what is the rate of the faster train? (Round your answer to the nearest integer).

Found 2 solutions by Solver92311, MathLover1:
Answer by Solver92311(821) About Me  (Show Source):
You can put this solution on YOUR website!


Let the faster train's speed be represented by . Then the slower train's speed must be .

Furthermore, because distance is equal to rate times time, the distances traveled by the two trains in two hours are and .

Since the trains are traveling at right angles to each other, these two distances are the legs of a right triangle where we are given that the hypotenuse measures 42.80 miles.

Using the Pythagorean Theorem:



Simplify and solve the quadratic for , remembering to round to the nearest integer when all of your calculations are complete.

John

My calculator said it, I believe it, that settles it

From
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Answer by MathLover1(20850) About Me  (Show Source):
You can put this solution on YOUR website!

Their speeds are r and+r-4, in miles per hour.
The distance traveled for each in the 2 hours are 2r and 2%28r%2B7%29
We know that
%282x%29%5E2%2B%282%28x-4%29%29%5E2=42.80%5E2+
4x%5E2%2B4%28x-4%29%5E2=1831.84
4x%5E2%2B4%28x%5E2-8x%2B16%29=1831.84
4x%5E2%2B4x%5E2-32x%2B64=1831.84
8x%5E2-32x%2B64=1831.84
x%5E2-4x%2B8=228.98
x%5E2-4x%2B8-228.98=0
x%5E2-4x-220.98=0.......using quadratic formula we get
x-12.9993->disregard negative solution
x16.9993 -> round it x=17mph