My Math Forum Snail problem... find the equation algebrically..

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 September 10th, 2007, 04:57 PM #1 Joined: Sep 2007 Posts: 2 Thanks: 0 Snail problem... find the equation algebrically.. A snail decides to climb a 12 meter well. Every day, he climbs 3 meters in the daytime and slides 2 meters at night. After how many days will he finally arrive at the other side of the well?
September 10th, 2007, 05:43 PM   #2
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Re: Snail problem... find the equation algebrically..

Quote:
 Originally Posted by helpmeplz! After how many days will he finally arrive at the other side of the well?
That depends on whether I salt it or not.

What do you have so far?

September 11th, 2007, 01:36 PM   #3
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Re: Snail problem... find the equation algebrically..

Quote:
 Originally Posted by helpmeplz! A snail decides to climb a 12 meter well. Every day, he climbs 3 meters in the daytime and slides 2 meters at night. After how many days will he finally arrive at the other side of the well?
After 9 days the snail will be at the 9 meter mark. On the 10th day it will reach the top - hopefully it won't slide back any more.

 September 11th, 2007, 04:10 PM #4 Joined: Dec 2006 Posts: 1,111 Thanks: 0 Suppose that the rate at which the snail traveled decreased at a non-constant rate depending upon how long he had been traveling, and also depending upon the amount of salt being poured on him? :P
September 11th, 2007, 04:42 PM   #5

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Re: Snail problem... find the equation algebrically..

Quote:
Originally Posted by mathman
Quote:
 Originally Posted by helpmeplz! A snail decides to climb a 12 meter well. Every day, he climbs 3 meters in the daytime and slides 2 meters at night. After how many days will he finally arrive at the other side of the well?
After 9 days the snail will be at the 9 meter mark. On the 10th day it will reach the top - hopefully it won't slide back any more.
Yeah I get it but how do you do it algebrically? I need an equation.

September 11th, 2007, 05:05 PM   #6
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Quote:
 Originally Posted by Infinity Suppose that the rate at which the snail traveled decreased at a non-constant rate depending upon how long he had been traveling, and also depending upon the amount of salt being poured on him? :P
Ooh, differential equations. I like.

September 12th, 2007, 12:49 PM   #7
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Re: Snail problem... find the equation algebrically..

[quote=helpmeplz!]
Quote:
Originally Posted by mathman
Quote:
 Originally Posted by "helpmeplz!":3fjk7njk A snail decides to climb a 12 meter well. Every day, he climbs 3 meters in the daytime and slides 2 meters at night. After how many days will he finally arrive at the other side of the well?
After 9 days the snail will be at the 9 meter mark. On the 10th day it will reach the top - hopefully it won't slide back any more.
Yeah I get it but how do you do it algebrically? I need an equation.[/quote:3fjk7njk]
H(n)=3+(n-1), where H is height after n days. Since you want H(n)=10, I think you can do the rest.

 September 12th, 2007, 01:38 PM #8 Joined: Aug 2007 From: turkey Posts: 57 Thanks: 0 11 day
September 12th, 2007, 04:00 PM   #9
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Quote:
 Originally Posted by helpmeplz! After how many days will he finally arrive at the other side of the well?
I don't understand. The snail is simply climbing upwards, so why does it ever reach the other side of the well? The standard (but tricky) problem of this type specifies a wall rather than a well, and you have to calculate how long it takes the snail to get to the point directly on the other side of the wall from the point where the snail started (so you have to include the time needed for the descent of the other side).

October 2nd, 2007, 11:20 AM   #10

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Quote:
Originally Posted by skipjack
Quote:
 Originally Posted by helpmeplz! After how many days will he finally arrive at the other side of the well?
I don't understand. The snail is simply climbing upwards, so why does it ever reach the other side of the well? The standard (but tricky) problem of this type specifies a wall rather than a well, and you have to calculate how long it takes the snail to get to the point directly on the other side of the wall from the point where the snail started (so you have to include the time needed for the descent of the other side).
lol so the distance from it started point to finish point is 24 meters =) how ever I believe the question maken by just for 12 meters.

October 2nd, 2007, 11:26 AM   #11

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Re: Snail problem... find the equation algebrically..

[quote=mathman]
Quote:
Originally Posted by helpmeplz!
Quote:
Originally Posted by mathman
Quote:
 Originally Posted by "helpmeplz!":1xq0tgc2 A snail decides to climb a 12 meter well. Every day, he climbs 3 meters in the daytime and slides 2 meters at night. After how many days will he finally arrive at the other side of the well?
After 9 days the snail will be at the 9 meter mark. On the 10th day it will reach the top - hopefully it won't slide back any more.
Yeah I get it but how do you do it algebrically? I need an equation.
H(n)=3+(n-1), where H is height after n days. Since you want H(n)=10, I think you can do the rest.[/quote:1xq0tgc2]

Re u sure this equation is giving the general solution? So if we think we got 12meters to take and if we got [one in a day] 3 steps up & 2 steps down( totally 1 step up) in 9 days we take 9 meters and 10th day first of all we ll take 3 steps up and we re 12 meters up already. Now c it at the solution;

u say H(n)=10 so then 3+(n-1)=10 and we've got n=8 here :/ I thnk thats not true.

 October 2nd, 2007, 01:31 PM #12 Global Moderator   Joined: Dec 2006 Posts: 10,491 Thanks: 29 I think "10" was just "12" mistyped. Here's the trickier problem. Forget algebra; just try to solve it correctly. A snail decides to climb a 20 foot wall (whose width may be ignored) and then climb down the other side of the wall. He can climb up 3 feet in the daytime, but slides down 2 feet at night. Each day consists of 12 hours of daytime followed by 12 hours of night-time, so the snail is 1 foot up the wall at the end of the first 24-hour day. After how long will he finally arrive at the foot of the other side of the wall? (I've used feet to distinguish this problem from the previous one.) Boring answers are wrong; you will know when you have the right answer!
October 3rd, 2007, 10:46 AM   #13

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Quote:
 Originally Posted by skipjack I think "10" was just "12" mistyped. Here's the trickier problem. Forget algebra; just try to solve it correctly. A snail decides to climb a 20 foot wall (whose width may be ignored) and then climb down the other side of the wall. Every day, he climbs 3 feet in the daytime and slides 2 feet at night. After how long will he finally arrive at the foot of the other side of the wall? (I've used feet to distinguish this problem from the previous one.) Boring answers are wrong; you will know when you have the right answer!

lol it can never arrive at the foot of the other side of the wall 'coz when it ll reach at the top of the wall it ll be 17th day and on the 18th day "climbin 3 feet in the daytime and slides 2 feet at the night" means ll be different(opposite)for it. thats why it can never reach to the foot point of the otherside of the wall.

October 3rd, 2007, 12:33 PM   #14
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Quote:
 Originally Posted by Enochiche . . . it. . .'ll be different(opposite)for it.
That doesn't make sense. The wall's thickness can be ignored, so the snail can certainly descend on the other side of the wall after reaching the top. However, I changed the wording slightly to remove any suggestion that the snail can't switch from ascending to descending. You should, of course, assume the snail doesn't make any unnecessary detours!

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