The speed of a moving walkway is about 3.5 feet per second. Walking on the moving walkway, it takes Maria a total of 40 seconds to travel 70 feet with the movement of the walkway and then back again against the movement of the walkway. What is Maria's normal walking speed?
Let her normal walking speed =W
Her walking speed WITH the walkway=W + 3.5
Her walking speed AGAINST the walkway =W - 3.5
Let the time it took her to walk with the walkway=T
The time it took her to walk against the walkway =40 - T
T * [W + 3.5] + [40 - T] * [W - 3.5] =70................(1)
[70/2] / [W+3.5] + [70/2] / [W-3.5]=40...............(2), solve for T, W.
T =4.3846 seconds
W =4.4827 =~4.5 feet/sec - her normal walking speed.