Question 200818
The moving sidewalk at Chicago's airport moves 1.8 ft/sec.
 Walking on the moving sidewalk, Joe travels 105 ft forward in the time it takes
 to travel 51 ft. in the opposite direction.
 How fast would Joe be walking on a non-moving sidewalk?
:
Let s = speed on a non-moving sidewalk
:
(s+1.8) = speed moving with it
(s-1.8) = speed moving against it
:
Write a time equation: Time = dist/speed
:
{{{105/((s+1.8))}}} = {{{51/((s-1.8))}}}
Cross multiply
105(s-1.8) = 51(s+1.8)
105s - 189 = 51s + 91.8
105s - 51s = 91.8 + 189
54s = 280.8
s = {{{280.8/54}}}
s = 5.2 ft/sec on an ordinary sidewalk
:
:
Check solution by find that the times are equal
105/(5.2+1.8) = 15 sec
51/(5.2-1.8) = 15 sec