<PRE><B>Question 814874</B>
The rate of a small aircraft in calm air is 125mph if the wind is currently blowing south at a rate of 10mph how far north can a pilot fly the plane and return it with 2hrs?
:
let d = one way dist to return in 2hrs
:
Write a time equation, time = dist/speed
:
time up + time back = 2hrs
{{{d/((125-10))}}} + {{{d/((125+10))}}} = 2
:
{{{d/115}}} + {{{d/135}}} = 2
multiply by
115*135, resulting in
135d + 115d = (135)(115)*2
250d = 31050
d = 31050/250
d = 124.2 mi north
:
:
Confirm this by finding the time each way
124.2/115 = 1.08 hrs
124.2/135 =  .92
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total time: 2 hrs</PRE>