If a spider fell to the bottom of a 50-foot well,...

[bamacre]

If a spider fell to the bottom of a 50-foot well, and each day climbed up three feet and slipped back two, how many days would it take the spider to get out of the well?

(Hint) The answer is not 50 days.

I read this in a Forbes magazine in an article about Bill Gates and the competition for high IQ employees.

My first answer was 50 days, until I saw the hint. I have now thought of another answer that seems somewhat logical, but I cannot find a definite answer (google came up empty).

 

[Zim Hosein]

Syringer!

 

[Schadenfroh]

Did someone say Syringer?

 

[Black88GTA]

48 days?

On the 48th day, he starts at foot 47. He climbs 3 feet, and is out - so doesn't slip back two.

 

[ViRGE]

Pft, 48 days.

 

[her209]

Its 48 days.

 

[BrianH1]

51. 50 would be to get to the top (edge)


edit: whoops im wrong. guess im not working for MS

 

[bamacre]

Originally posted by: Black88GTA
48 days?

On the 48th day, he is at foot 47. He climbs 3 feet, and is out - so doesn't slip back two.

Exactly what I was thinking. But then the question is somewhat flawed.

 

[imported_LoKe]

51. On the 50th day, he'd make it to the top, then slip back two feet. No?

They never say he slips back because he's in the well, he just slips back. Therefore 48 is not necessarily the correct answer.

 

[FleshLight]

NM =)

 

[FeuerFrei]

47 days

 

[KingofCamelot]

Originally posted by: LoKe
51. On the 50th day, he'd make it to the top, then slip back two feet. No?

They never say he slips back because he's in the well, he just slips back. Therefore 48 is not necessarily the correct answer.

Well, I think its safe to assume he is sliding because he is on a vertical wall. If the spider is out of the well it would have to slip horizontally, then vertically, and then just stop on the wall.

 

[iamtrout]

NEVER. HE DIES BEFORE HE CAN GET OUT.

 

[imported_LoKe]

Originally posted by: KingofCamelot

Originally posted by: LoKe
51. On the 50th day, he'd make it to the top, then slip back two feet. No?

They never say he slips back because he's in the well, he just slips back. Therefore 48 is not necessarily the correct answer.

Well, I think its safe to assume he is sliding because he is on a vertical wall. If the spider is out of the well it would have to slip horizontally, then vertically, and then just stop on the wall.

Then the question is indeed flawed. The details are important.

 

[PlatinumGold]

it's basically the same as saying, 10 tons per truckload, 45 tons to move. how many trips.

obviously it's 5, but many people have said 4.5.

 

[rahul]

Is it necessary for the spider to climb 3' first and then slide back 2'? What if it actually climbed 3" slid back 2" and so on, totalling 36" over the course of 24 hours? In this case it would take 50 days.

 

[Rapidskies]

48 ftw!

 

[Xylitol]

51 days

 

[GoingUp]

47 days

 

[KingofCamelot]

I've heard this before, and I remember the answer being 48. The way I remember it, the spider climbs 3 feet every day, and slides back 2 feet every night. When put that way the only logical answer is 48 days.

 

[mercanucaribe]

48 days?

 

[CheesePoofs]

Originally posted by: iamtrout
NEVER. HE DIES BEFORE HE CAN GET OUT.

bingo

 

[BigJ]

Originally posted by: PlatinumGold
it's basically the same as saying, 10 tons per truckload, 45 tons to move. how many trips.

obviously it's 5, but many people have said 4.5.

How so? On the 49th day for example, he's going to go past the 50ft barrier of the well and then where to the 51st foot? A foot above the well? Then on the 50th day, he's going to go two feet above the well?

 

[Syringer]

Originally posted by: Zim Hosein
Syringer!

 

[villageidiot111]

Its 48 because the spider climbs up three feet then falls down two feet. So for a portion of the day the spider is at 50ft, which is the top.