SOLUTION: bob takes escalator from subway to street level. if he runs-up 8 stairs it takes him 46.5 seconds. if he runs-up 13 stairs it takes him 39.0 seconds.
How long will it take bob
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-> SOLUTION: bob takes escalator from subway to street level. if he runs-up 8 stairs it takes him 46.5 seconds. if he runs-up 13 stairs it takes him 39.0 seconds.
How long will it take bob
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Question 642107: bob takes escalator from subway to street level. if he runs-up 8 stairs it takes him 46.5 seconds. if he runs-up 13 stairs it takes him 39.0 seconds.
How long will it take bob to get to the top if he doesn't run at all? Answer by ankor@dixie-net.com(22740) (Show Source):
You can put this solution on YOUR website! bob takes escalator from subway to street level.
if he runs-up 8 stairs it takes him 46.5 seconds.
if he runs-up 13 stairs it takes him 39.0 seconds.
How long will it take bob to get to the top if he doesn't run at all?
:
let s = no. of steps traveled by the escalator
then
(s+8) = no. of steps when he runs up in 46.5 sec
and
(s+13) = no. of steps when he runs up in 39 sec
:
Let d = total distance traveled by the escalator
then = 46.5
d = 46.5(s+8)
and = 39
d = 39(s+13)
:
d=d, therefore we can combine the equations
46.5(s+8) = 39(s+13)
46.5s + 372 = 39s + 507
46.5s - 39s = 507 - 372
7.5s = 135
s = 135/7.5
s = 18 steps
:
Find the time (t) when just letting escalator move
Time varies inversely with speed = =
cross multiply
18t = 39 * 31
18t = 1209
t = 1209/18
t = 67.2 seconds if he just ride it
