[Guest]

'A' goes walks a escalator which has 30 steps and both the escalator and the A are moving and A walks only 20 steps and reaches above and now comes B who is half as fast as A ,on the same escalator

SO now tell that how many steps should B make to reach to cross the escalator ?

[preflop]

I think it is

15 steps for B.

A is walking at a rate of 2 steps for every 1 step the escalator makes. (A took 20 steps, and escalator moved 10 more for a total of 30).

So if B walks half as fast as A, B should be taking only 1 step per escalator step. So when B makes 15 steps, the escalator will make 15 steps.

[Guest]

B could take any number of steps to reach across the escalator. Since the thing is automatic, B could just relax, stay still and reach across without actually moving a muscle.

So the answer is n steps where 0<= n <= 15 (see preflop's explanation)

Edited September 26, 2011 by jagdmc

[Guest]

I'm thinking that the puzzle data is actually incomplete. The phrase "half as fast" has not been determined to be A's and B's step frequencies relative to the escalator's movement (as in preflop's explanation), or B's leg speed relative to the leg speed of A. For example, a change in rise height of each stair would cover a greater difference in diagonal escalator movement with relative leg speed variations than with relative step frequency variations - wouldn't it?

[Guest]

<p> </p>

<p>

</p>

<p>

B could take any number of steps to reach across the escalator. Since the thing is automatic, B could just relax, stay still and reach across without actually moving a muscle.</p>

<p>So the answer is n steps where 0&lt;= n &lt;= 15 (see preflop's explanation)

</p>

<p>

</p>

<p> </p>

<p> </p>

<p>He can't just not move a muscle. If his speed is defined, then he has to be moving, right?</p>

<p> </p>

<p> </p>

<p> </p>

<p>

</p>

<p>I'm thinking that the puzzle data is actually incomplete. The phrase &quot;half as fast&quot; has not been determined to be A's and B's step frequencies relative to the escalator's movement (as in preflop's explanation), or B's leg speed relative to the leg speed of A. For example, a change in rise height of each stair would cover a greater difference in diagonal escalator movement with relative leg speed variations than with relative step frequency variations - wouldn't it?</p>

<p>

</p>

<p> </p>

<p>Quite simply put, consider it a walkway. They are flat moving belt on which people walk. So the total speed is velocity of belt+velocity of person.<br />

Use simple logic here. Whatever is not defined, initialize with defaults.<br />

The belt is now flat with each step being of 1 unit, and belt is composed of 30 units.<br />

Simply stating<br />

Va=2Vb</p>

<p>If t= time, A covers 20 steps in t, while remaining 10 are covered by belt, to make a total distance travelled =30.</p>

<p>So, Va=2V(belt)<br />

<br />

This means Vb=V(belt)<br />

<br />

Now, in time t1, B covers x steps, while belt also covers x steps since they have the same speed.</p>

<p>To make a total distance of 30 units, x=15.<br />

<br />

So, B must take 15 steps.</p>

<p> </p>

<br />

[Guest]

why am I getting an HTML sort of tags?

[robo]

15 steps.

A takes 20 steps. The escalator goes up 10 steps. So escalator is half as fast as A.

This means, B and escalator are equally fast. So B has to take half of the total steps to reach the top, i.e. 15 steps.

[Guest]

10

[Guest]

<p> </p>

<p></p>

<p> </p>

<p> </p>

<p>He can't just not move a muscle. If his speed is defined, then he has to be moving, right?</p>

<p> </p>

<p> </p>

<p> </p>

<p></p>

<p> </p>

<p>Quite simply put, consider it a walkway. They are flat moving belt on which people walk. So the total speed is velocity of belt+velocity of person.<br />

Use simple logic here. Whatever is not defined, initialize with defaults.<br />

The belt is now flat with each step being of 1 unit, and belt is composed of 30 units.<br />

Simply stating<br />

Va=2Vb</p>

<p>If t= time, A covers 20 steps in t, while remaining 10 are covered by belt, to make a total distance travelled =30.</p>

<p>So, Va=2V(belt)<br />

<br />

This means Vb=V(belt)<br />

<br />

Now, in time t1, B covers x steps, while belt also covers x steps since they have the same speed.</p>

<p>To make a total distance of 30 units, x=15.<br />

<br />

So, B must take 15 steps.</p>

<p> </p>

<br />

So, in order to solve this puzzle, we need to change its conditions (a la Captain Kirk and the "Kobyashi Maru" no-win scenario)?

[Guest]

the answer is 15. If the number of steps is 30 and A takes 20 the remainder 10 could be considered the "time traveled", as B is Half as slow as A, this distance should be halved and Minused off A's steps. Logical?

Edited September 27, 2011 by Caalight

[Guest]

I'm thinking that the puzzle data is actually incomplete. The phrase "half as fast" has not been determined to be A's and B's step frequencies relative to the escalator's movement (as in preflop's explanation), or B's leg speed relative to the leg speed of A. For example, a change in rise height of each stair would cover a greater difference in diagonal escalator movement with relative leg speed variations than with relative step frequency variations - wouldn't it?

no

Edited September 27, 2011 by Caalight

[Guest]

The answer is

10!.. The escalator is 30 steps total. in the time A takes 20 steps, he is at the top, so the escalator moves 10. B takes twice as long, so the escalator will have moved 20 steps, so B's slow self will only have time to take 10 steps before reaching the top.

[bhramarraj]

The answer is

10!.. The escalator is 30 steps total. in the time A takes 20 steps, he is at the top, so the escalator moves 10. B takes twice as long, so the escalator will have moved 20 steps, so B's slow self will only have time to take 10 steps before reaching the top.

You said “B takes twice as long, so the escalator will have moved 20 steps,…..”

Edited September 28, 2011 by bhramarraj

[bhramarraj]

You said “B takes twice as long, so the escalator will have moved 20 steps,…..”

You forgot:

Time taken by B to walk 20 steps = twice the time taken by A to walk 20 steps = twice the time taken by escalator to move 10 steps.

So the time taken by B to walk 10 steps = the time taken by A to walk 20 steps = the time taken by escalator to move 10 steps.

I think it is clear now that B will have to walk only 15 steps to reach the top.

[bhramarraj]

You forgot:

Time taken by B to walk 20 steps = twice the time taken by A to walk 20 steps = twice the time taken by escalator to move 10 steps.

So the time taken by B to walk 10 steps = the time taken by A to walk 20 steps = the time taken by escalator to move 10 steps.

I think it is clear now that B will have to walk only 15 steps to reach the top.

Sorry, I don't know why spoiler was not working

Edited September 28, 2011 by bhramarraj

[Guest]

Yea, i tried to edit my comment yesterday, realizing shortly after i posted that i was wrong, but the site was acting sluggish. Whoops!