Jeff and Sharon drove for 4 hours with a wind speed of 10 mph. Traveling against the same wind speed, it took them 6 hours to make the return trip. How fast were they traveling in still air?
Answer

60 mph

65 mph

55 mph

50 mph

Question

Jeff and Sharon drove for 4 hours with a wind speed of 10 mph. Traveling against the same wind speed, it took them 6 hours to make the return trip. How fast were they traveling in still air?
Answer
		
60 mph
		
65 mph
		
55 mph
		
50 mph

anonymous · Answer

If x is her speed without wind, then x+10 is her speed with the wind, and x-10 is her speed against the wind. Using rate x time = distance, and since the distances are the same in both directions, we have 4(x+10)=6(x-10).  Solving for x give 50 mph.

jim_thompson5910 · Answer

Trip there:
d=rt
d=(x+10)*4
d=4x+40

Trip back:
d=rt
d=(x-10)*6
d=6x-60
--------------------

d=4x+40

6x-60=4x+40

6x=4x+40+60

6x-4x=40+60

2x=40+60

2x=100

x=(100)/(2

x=50

So their speed in still air is 50 mph