Problema Solution
An ultralight plane had been flying for 40 min when a change of wind direction doubled its ground speed. The entire trip of 160 mi took 2 h. How far did the plane travel during the first 40 min?
Answer provided by our tutors
Set up some equations, then substitute and solve.
Distance = rate x time, so
160 mi = 2/3 x + 1 2/3 y
(since 40 min = 2/3 h)
Also, we know that speed y = 2x... so now substitute and solve!
160 = 2/3(x) + 1 2/3(2x)
160 = 2/3 x + 10/3 x
160 = 12/3 x = 4 x
x = 40 mi/h
Since y = 2x,
y = 80 mi/h