word problem

[Christine]

Maureen can fly her plane 250 miles with the wind in the same time she can fly it 200 miles against the wind. If the speed of her plane is 90 miles/hour, what is the wind speed?

 

[stapel]

Use the standard "uniform rate" equation, "d = rt", letting "w" stand for the windspeed.

. . . . .tailwind:

. . . . .distance: 250
. . . . .rate: 90 + w
. . . . .time: 250/(90 + w)

. . . . .headwind:

. . . . .distance: 200
. . . . .rate: 90 - w
. . . . .time: 200/(90 - w)

Since the times are the same, set the "time" expressions equal, and solve.

Hope that helps a bit.

Eliz.

 

[Denis]

Another way:

with no wind, distance @90 = (250+200)/2 = 225;
90 = 225/t : t = 2.5 hours

w = wind
90 + w = 250/2.5
w = 10