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s*******n
发帖数: 66 | 1 There is a escalator and 2 persons move down it.A takes 50 steps and B takes
75 steps while the escalator is moving down.Given that the time taken by A
to take 1 step is equal to time taken by B to take 3 steps.Find the no. of
steps in the escalator while it is stationary.
Is the answer 100? thanks! | b******v
发帖数: 1493 | 2 My answer is also 100.
Assume it takes 3 seconds for A, and 1 second for B to take 1 step.
Assume the speed of escalator is x steps/second.
Then we have it takes A 3*50=150, and takes B 1*75=75 seconds to move down.
Thus we have
150*(1/3+x) = 75*(1+x) = the height in no. of steps
So x = 1/3.
Therefore the no. of steps is 75*(1+x) = 100.
takes
A
【在 s*******n 的大作中提到】
: There is a escalator and 2 persons move down it.A takes 50 steps and B takes
: 75 steps while the escalator is moving down.Given that the time taken by A
: to take 1 step is equal to time taken by B to take 3 steps.Find the no. of
: steps in the escalator while it is stationary.
: Is the answer 100? thanks!
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