SOLUTION: An airplane flies 410 miles with the wind and 310 against the wind in the same length of time. If the speed of the wind is 40, what is the speed of the airplane in still air?
A.)
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A.)
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Question 994514: An airplane flies 410 miles with the wind and 310 against the wind in the same length of time. If the speed of the wind is 40, what is the speed of the airplane in still air?
A.). 293mph. B). 288mph. C). 124mph. D). 278mph
I have tried this:
X=d/t.
X=410 -40
X=370
X=310+40
X=350
You can put this solution on YOUR website! .
t=time; d=distance; r=rate
t=d/r
.
With wind:
t=410mi/r+40
Against wind:
t=310mi/r-40
.
Since time in both directions is the same:
410mi/r+40=310mi/r-40
410(r-40)=310(r+40)
410r-16400=310r+12400
100r=28800
r=288
.
ANSWER: The rate of the plane in still air is 288 mph.
Uniform Rates Travel Rule, RT=D to relate rate, time, distance;
also can be used as R=D/T.
Direction speed time distance
WITH r+w t m
AGAINST r-w t n
See that the same number in the same variable t is used for both directions. The question asks for r, but not for t.
Direction speed time distance
WITH r+w t=m/(r+w) m
AGAINST r-w t=n/(r-w) n
Equate the two formulas for time t:
This equation uses only one unknown variable, r, which is what the question asks to find. Solve the equation for r.