Question 193694: When Kelly is not on the moving sidewalk, she can walk the length of the sidewalk in 3 minutes. If she stands on the sidewalk as it moves, she can travel the length in 2 minutes. If Kelly walks on the sidewalk as it moves, how many minutes will it take her to travel the same distance? Assume she always walks at the same speed.
Help is appreacited. Thanks
Answer by RAY100(1637)   (Show Source):
You can put this solution on YOUR website! velocity=distance /time
v1=d/3
v2=d/2
v1+v2=d/t (sum of rates equals total rate)
d/3+d/2=d/t
mult by 6t,,,,,divide by d
2t+3t=6
5t=6
t=1.2 min
check
distance = velocity *time
d1 +d2=d (distance at each rate sum to total distance)
(d/3)1.2+(d/2)1.2=d
.4d+.6d=d
d=d ,,,ok
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