Question 648464
THE SPEED OF A MOVING WALKAWAY IS TYPICALLY ABOUT 2.5 PER SECOND.
 WALKING ON SUCH A MOVING WALKAWAY, IT TAKES KAREN A TOTAL OF 40 SECONDS TO
 TRAVEL 50 FEET WITH THE MOVEMENT OF THE WALKAWAY AND THEN BACK AGAIN AGAINST
 THE MOVEMENT OF THE WALKAWAY.
 WHAT IS KAREN'S NORMAL WALKING SPEED?
:
Let w = normal walking speed in ft/sec
Then
(w+2.5) = effective speed with the walkway
and
(w-2.5) = effective speed against the walkway
:
Write a time equation: time = dist/speed
:
Time with + time against = 40 sec
{{{50/((w+2.5))}}} + {{{50/((w-2.5))}}} = 40
:
Multiply by (w+2.5)(w-2.5); results:
50(w-2.5) + 50(w+2.5) = 40(w-2.5)(w+2.5)
:
50w - 125 + 50w + 125 = 40(w^2-6.25)
:
100w = 40(w^2-6.25)
divide both sides by 20
5w = 2(w^2-6.25)
5w = 2w^2 - 12.5
A quadratic equation
2w^2 - 5w - 12.5 = 0
Use the quadratic formula to find w; a=2; b=-5; c=-12.5
:
I got a positive solution ~ 4.045 ft/sec, normal walking speed, see what you get