Question

[6.05] An airplane flew 3 hours with a 40 mph head wind. The return trip with a tail wind of the same speed took 2 hours. Find the speed of the plane in still air.

180 mph

200 mph

220 mph

240 mph

Answer 1

is the answer 240?

Answer 2

Let s = still air speed of plane
Distance traveled on outward trip = (s - 40) * 3 = d
Distance traveled on return trip = (s + 40) * 2 = d
3(s - 40) = 2(s + 40)
3s - 120 = 2s + 80

Can you solve for s ?

Answer 3

yes and i got 40 as my answer

Answer 4

3s - 120 = 2s + 80
Subtract 2s from each side
(3s - 2s) -120 = (2s - 2s) + 80
s -120 = 0 + 80
Add 120 to each side
s - (120 +120) = 80 + 120
s = 80 + 120 = ? mph

Answer 5

200

Answer 6

200 mph is the correct choice.

Answer 7

thanks :)

Answer 8

You're welcome :)