Fishtanks and Highrises

[Ăɍȼẗîȼ]

I have a riddle:

 

I have a 101 floor high rise, 2 plastic fish tanks, and an elevator that takes me to any floor on the building instantly.

 

Due to safety regulations of my country, I have to determine a floor X, where all floors above X (including X), where I dropped a fish tank out of, it will break. At all floors below X, if I dropped a fish tank out of that floor, the fish tank won't break.

 

What is the most efficient way of determining X?

 

Answer to my riddle gets 3 REPS from me.

 

Best Answer so far: Blue Thunder: 20 tries in the worst case.

 

(MODS: I'm not sure if this should be in this section, if not, please move.)

[Blue Lightning]

Go to the second floor. drop it. If it breaks, there you go, if it doesnt, go to the first floor and try with the floor above until you do it.

 

Amirite?

[Ăɍȼẗîȼ]

That will all you to find X in 51 tries in the absolute worst case.

 

If you have to drop every other floor until floor 100, where it breaks.

 

Then you have to go back up to test floor 99... yeah, 51 tries.

 

Try to be better.

[Willieh]

I can't math. :(

[Blue Lightning]

What about asking Ăɍȼẗîȼ for the answer? that will let me know the first time I try

 

hmmmm drop it from floor 42

[iwrestledabearonce]

Drop it from floor X

Cause X is below floor 1, meaning that it is the ground.

 

 

???

[Blue Lightning]

I know, do what i said in the first but every other floor

[Ăɍȼẗîȼ]

Drop it from floor X

Cause X is below floor 1' date=' meaning that it is the ground.

 

 

???

[/quote']

 

But you don't know x.

[Blue Lightning]

what about me?

[iwrestledabearonce]

Drop it from floor X

Cause X is below floor 1' date=' meaning that it is the ground.

 

 

???

[/quote']

 

But you don't know x.

 

X is the ground.

Cause you can't go below floor 1.

[Ăɍȼẗîȼ]

What about asking Ăɍȼẗîȼ for the answer? that will let me know the first time I try

 

hmmmm drop it from floor 42

 

So it breaks, you do it in 42 tries. what if it doesn't break?

[El Beasto Perezoso]

Start at the first floor, and drop the fish tank out th e window until you reach a floor where it breaks. That floor is X

[NeoDemonX]

It is the ocean people, I think it is

[Ăɍȼẗîȼ]

Start at the first floor' date=' and drop the fish tank out th e window until you reach a floor where it breaks. That floor is X

[/quote']

 

Nice job. If it doesn't break until floor 101, then you did it in 101 tries.

 

I want most efficient.

[rustyowl]

Go to floor 51, and if it breaks, go down until you find a floor that doesn't break. If it doesn't break at floor 51, go up until it does.

[El Beasto Perezoso]

Go to the floor in the middle of the building (vertically) and drop it out the window. If it survives, go to the floor directly in the middle between that floor and the Floor 101. If it breaks, go to the floor directly in the middle between that floor and Floor 1. Repeat this process until Floor X is found.

[Ăɍȼẗîȼ]

Go to floor 51' date=' and if it breaks, go down until you find a floor that doesn't break. If it doesn't break at floor 51, go up until it does.

[/quote']

 

Nice job, it does it in 51 tries. Which I've said isn't the most efficient.

 

 

 

Go to the floor in the middle of the building (vertically) and drop it out the window. If it survives' date=' go to the floor directly in the middle between that floor and the Floor 101. If it breaks, go to the floor directly in the middle between that floor and Floor 1. Repeat this process until Floor X is found.

[/quote']

 

Drop at 51, it breaks.

 

Drop at 25, it breaks again.

 

Now you have no fishtanks, and you don't know X.

[rustyowl]

Hint?

[Ăɍȼẗîȼ]

People should be smart enough. It's not a difficult riddle. You just need to think a bit.

[El Beasto Perezoso]

Start on Floor 1, and go up to Floor 4, where you drop a tank. If it survives, go up 3 floors and drop it again. If it breaks, drop the other tank from the floor directly below. If it breaks there, Floor X is the floor directly beneath that floor, if it survives, Floor X is the floor directly above that floor. (I.E. Tank survives Floor 4, goto Floor 7. Breaks Floor 7, goto Floor 6. Breaks Floor 6, Floor X is Floor 5.

[Raelen]

Does the solution of this riddle have anything to do with the fish tank being plastic?

[Ăɍȼẗîȼ]

Start on Floor 1' date=' and go up to Floor 4, where you drop a tank. If it survives, go up 3 floors and drop it again. If it breaks, drop the other tank from the floor directly below. If it breaks there, Floor X is the floor directly beneath that floor, if it survives, Floor X is the floor directly above that floor. (I.E. Tank survives Floor 4, goto Floor 7. Breaks Floor 7, goto Floor 6. Breaks Floor 6, Floor X is Floor 5.

[/quote']

 

Well...

 

That gets it done in 35 tries. You go up until floor 99, where it breaks, and you go to floor 97, and 98 to find X.

 

Not most efficient solution.

 

@ Raelen: A glass fish tank will break too easily for the problem to be realistic.

[Blue Lightning]

What about asking Ăɍȼẗîȼ for the answer? that will let me know the first time I try

 

hmmmm drop it from floor 42

 

So it breaks' date=' you do it in 42 tries. what if it doesn't break?

[/quote']

 

I meant the one after that one the skipping every other floor. that would could it in half

 

 

I know

 

drop from 11, 22, 33,44 and so on until it breaks. Then between the 10 floor interval keep dropping the other one. that means at max 20 tries

 

 

EDIT: Post number 1234. I win

[Ăɍȼẗîȼ]

Okay... that takes you 20 tries.

 

Not most efficient way.

[El Beasto Perezoso]

No matter how I do it, the lowest number of tries I can get is 19. Is that the lowest number?