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January 13, 2011

Climbing Snail


A snail is at the bottom of a 20 meters deep pit. Every day
the snail climbs 5 meters upwards, but at night it slides
4 meters.

The Question: How many days does it take before the snail
reaches the top of the pit?

16 comments:

André Meneses said...

16 days

Surya4u said...

15 and 1/2 day or you can say 16 days

Swadhi said...

On the 16th day he'll reach the top

Anonymous said...

20 days

Patricia said...

being that every day it only gains 1 meter then it should be 20 days

Babu vincent said...

its 16 days

on 14th day it would have dont its 14 feet journey...

on 15th - end of the DAY - it will touch 19 feet..

due to sliding it will come down to 15 th feet in the end of night

on 16th day it will reach 20th feet in day by travelling 4 feet...

Swadhi said...

But once he reaches the top of the pit (on the 16th day), why would he slide down again? He'd be on even ground! So it wouldn't be 20 days, it'd be 16, I think.

Anonymous said...

@swathi hope you aware of Gravity

Swadhi said...

I am aware of gravity, but gravity doesn't pull objects through EVEN ground. O_o

Babu vincent said...

right when it reaches 20 th feet it also come to the end of the top

as you say it might take one more day ??(max) to reach top..

you right as it is in 20th there is chance to come down because i hasnt reached the even ground..

so 17 days

Babu vincent said...

*to reach top to reach even place

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Affan Abdul Kadar said...

17 days to get out of the pit, but 16 days to reach the top of the pit.

Anonymous said...

Question says"reaches the top of the pit?" so the answer is 16 days not 17 days.

@ Baby Vincent.. in your answer you have said "on 16th day it will reach 20th feet in day by travelling 4 feet..." at end of the 15th day it was there at 15 feet height so it has to travel 5 feet to reach the top not 4 feet.

hem said...

25 days.

@Editor: Are these puzzles being given out to you as home work or something? Just wondering, since you are either hesitant to publish the answer or not sure yourself.

Anonymous said...

16 days