[Guest]

Hey peeps!

I was playing Resident Evil 0, and I came across one of those diary/document thingies.

Well, it talks about the leeches infected with the T virus, and um... how they've been reproducing and... stuff..

ANYHOO!

parts of this document are highlighted, and I don't know where I'll use this information, but these're the listed things worth mentioning.

First of all, the leeches double their population every hour.

February 3rd.

The scientist puts 4 leeches into his... containment thingie.

February 10th.

because of the numbers growing so much, the scientist hasn't been increasing food supply often enough, the leeches turn to cannibalism.

The scientist incresing the food supply, but not before two of the leeches are eaten.

March 7th.

Scientists tries giving the leeches live pray.

But half of the leeches are killed when the pray attacks back

the last enty of the document is on June 3rd.

so yeah.. uhh.. could anyone help me in figuring out how many leeches are alive at this time?

Thanks

[unreality]

how they reproduce from the beginning is important- do they "double" every "x amount of time"? It could be anything unless we have some of that data on their reproductive patterns

[Guest]

ooh... I'm not sure.

The document says "They double their numbers every hour" (the part I put in red is also in red in the document)

I took it as.. well,

like, first hour they go from 4 to 8, then 8 to 16, then 16 to 32, etc

[Guest]

I approximate somewhere in the neighborhood of:

10⁸⁷⁴ leaches

There are about 121 days (2904 hours) between the start of the experiment and the day the records end. They double every hour. The prey attacking back sets them back an hour. Lets consider the lost 2 to be negligible:

4 * 2^(2904-1) = 10^{log(4 * 2^(2904-1))} = 10^{log(4) + 2903*log(2)} =approx= 10^874.5 leaches

Of course this number is preposterous. For comparison, the number of atoms on earth is 'only' about:

8.87 x 10⁴⁹ atoms (http://pages.prodigy.net/jhonig/bignum/qaearth.html)

Edited August 19, 2008 by magicchamp

[Guest]

Here is the complete document:

     ********************

     Leech Growth Records

     ********************

     Found : Poison room in church


February 3rd, 1978.

- Administrated "T" into 4 leeches. Their will to survive leads them first to

parasitism and predation, then they breed and mulitply. Such single minded biology

makes them attractive candidates for bioweapons research. Afterwards, no major changes

observed.


February 10th, 1978.

- 7 days since the adminstration of the "T". Rapid growth to double former size, signs

of tranformation emerging. Spawning successful, they double their numbers in an hour,

but their ravenous appetites lead them to cannibalism. Hastened to incease food supply,

but lost 2.


March 7th, 1978.

- Provided them with live feed, but lost half when the live food fought back. However,

the leeches are learning from experience, and are beginning to exhibit group attack

behavior. They are also ceasing cannibalism. Their evolution is exceeding expectations.


April 22nd, 1978.

- The leeches no longer exhibit individual behavior, even when not feeding, they move as

a collective. They consume everything I offer with remarkable efficiency.


- April 30th,1978.

An employee has stumbled onto my experiments. Can a human be a food source? How will the

leeches respond?


June 3rd,1978

- A day worthy of commemoration. Today they began to mimic me! Surely they recognize

their father.. Wonderful children, No one will take you away..[/codebox]

cute story....

you have to take into account that halfway through the number of leeches are divided in half....so

someone who likes math do it.....

[Guest]

"assuming they write the documents the exact hour they started":

it starts with 4 leeches then multiplies by number of days (7), hours in a day (24), and by 2 because they double every hour

4*7*24*2=1,344-2=1,342

"also asuuming the 2 died the same hour the expiriment began"

then subtract 2 because they died and multiply by number of days (25), hours in a day (24), and by 2

1,342*25*24*2=1,610,400

"and of course asuuming half died the hour the expiriment began"

then divide by two because they ate half of each other, and multiply by number of days (87), hours in a day (24), and by 2

(1,610,400/2)*87*24*2=

3,362,515,200 leeches

Edited August 19, 2008 by D_moniK

[Guest]

im sorry my previous post was erroneous and it wont let me delete it

also it doesn't say that the leeches double every hour until February 10th before that they just double (according to the real documents posted by "Solemnraven" thanx btw it cleared up a lot of ?'s)

"assuming they write the documents the exact hour they started":

it starts with 4 leeches then doubles and 2 die

4*2=8-2=6

then they double every hour so: multiply by number of days (25), hours in a day (24), and by 2

6*25*24*2=7,200

"and of course assuming half died the hour the expiriment began"

then divide by two because their food killed half of them, and multiply by number of days (87), hours in a day (24), and by 2

(7,200/2)*87*24*2=

15,033,600 leeches

Edited August 19, 2008 by D_moniK

[Guest]

Feb 3: 4 Leeches

Feb 10: Begins with 8 Leeches, Loses 2 (total of 6), Finish the day with 6 x 2^23 (50,331,648 leaches)

Ultimately, you are looking at a series that will multiply the previous day's sum by 2^24. On March 7, it would again be 2^23 (lose one hour for the half being killed), but then continue multiplying daily by 2^24 until June 3rd. And I'm not doing all that math.

An alternate theory is that since there is only one mention of the spawning, he only attempted it once and was successful within one hour. With no further mentions of spawning, they would finish with only 3 (4 to start, 8 after the ONLY spawn, 2 lost to cannibalism, 1/2 of remaining (3 of 6) lost to live prey, thus leaving 3)

[Guest]

If we are to take into consideration "reality", then the darn slugs have a lifespan. To say they are all alive when the population reaches 10^874 is a little much.

I'll work on the math on my lunch here and see what I come up with.

[Guest]

There are 5807 leaches left on June 3rd. You add up the number of days and multiply by the number of leaches subtract the two lost and divide by the half that were killed by the prey. you get your answer.

[Guest]

Here's my math, with assumptions:

Feb 3rd: 4 leeches

Feb 10th: 6 leeches -- the population doubled, then they lost 2

Mar 7th: ~2.4897x10^181 leeches -- from 6*2^(25 days * 24 hours) -- initial 6 times 2 to the power (number of hours in which the population doubles). Eg in one hour, 2^1, the population is 6*2 or 12, two hours 2^2, or 4*6=24 leeches, etc.

Anything after this, they double from breeding and then lose half from the live bait, hence we've reached steady-state.

[Guest]

The amount of which they populate is never specified; otherwise my guess is 1 leach.

[Guest]

being that they double every hour, 7 days pass, 2 die, 26 days pass, another half are eaten/killed, 88 more days pass.

4.4601490376292058848932126031175e+43

[Guest]

Hi ... By my calculations, there are 3 leeches.

Started out with 4

Doubled once, and it took an hour to do so. = 8

Ate 2 = 6

lost half = 3

[Guest]

I think a few people are looking at the doubling of population as a multiplicative function when in fact it is an exponential function: http://en.wikipedia.org/wiki/Exponential_growth

Also, their doubling growth isn't documented until the Feb 10th. And if the population doubles, then gets cut in half you end up with the same number: 2*x/2 = (2/2)*x = x

[Guest]

but it says the population doubles every hour not its growth. are we reading it incorrectly?

[Guest]

I have reason to believe that it's a four digit number...

That reason is a combination lock with four numbers to put in.

I've found no other clue to the combination, all other doors are locked, so this must be where I've gotta go.

though, I also wonder why he would put the combination to the door the exact amount of leeches he had at (an unspecified) hour...

so I may be wrong

[Guest]

but it says the population doubles every hour not its growth. are we reading it incorrectly?

Ok, my bad. Growth and reproduction are two separate ideas mentioned in the journal. Growth being how large physically the leeches are getting, reproduction is how many of them they are. The term "Population Growth" usually refers to reproduction though.

[Guest]

yeah, he only mentions the leech's size once, when he said that they have doubled in size.

I think we are reading something wrong, because a four digit number seems very small for the math problem the way we're looking at it

EDIT: Or, the combination lock has nothing to do with this

Edited August 19, 2008 by Ploper

[Guest]

yeah, he only mentions the leech's size once, when he said that they have doubled in size.

I think we are reading something wrong, because a four digit number seems very small for the math problem the way we're looking at it

EDIT: Or, the combination lock has nothing to do with this

the lock has nothing to do with this

if you want the answer to what you need for the lock

385

[Guest]

makes a debatable puzzle though good work!

[Guest]

385

yeah, i got impatient, it's 4863 though for the lock.

though, I have no idea how the people who wrote the walkthrough came about that answer... so now I feel bad.... lol

makes a debatable puzzle though good work!

thanks... though, all I did was post a puzzle I didn't wanna solve on here.

I don't want to read ahead in walkthroughs, but I wonder where this document is needed.

Parts of it are highlighted which is the only reason it's driving me nuts

[Guest]

yeah, i got impatient, it's 4863 though for the lock.

though, I have no idea how the people who wrote the walkthrough came about that answer... so now I feel bad.... lol

thanks... though, all I did was post a puzzle I didn't wanna solve on here.

I don't want to read ahead in walkthroughs, but I wonder where this document is needed.

Parts of it are highlighted which is the only reason it's driving me nuts

ha.....

yeah i dont read them what i do is i type in firefox what i need, so for instance once you said combination lock i found one and typed in that and it brought me to the answer i gave you.....im guessing it changes though....which is why we got dif. answers supposedly it was found on the right corner of something.

sometimes games are too crazy in expecting you to know where to find the answer...

[Guest]

actually, the two ARE related.

The website I used has like 10 different walkthroughs. This one explains where 4863 is from.

I found the original document in a room this walkthrough calls "the poisoning room"

Round the corner and use the Dial on the metal door. If you read the

file you got from the Poisoning Room, you should know the combination.

If not, the combination is 4863. Go through the door...

so now I'm wondering how to look at the problem now, because the way I was looking at it, there is no way there would be 4863 leeches.

I'm going to look at the document again and see if..... I dunno, just see

Edited August 19, 2008 by Ploper

[Guest]

ohh, now I know where you got 835 from.

I wasn't specific about the lock I was opening.

I was trying to get to the room where that cable car is.

835 opens the breifcase with the handgun scope...

woo!

[Guest]

February 3rd, 1978.

- Administrated "T" into 4 leeches. Their will to survive leads them first to

parasitism and predation, then they breed and mulitply. Such single minded biology

makes them attractive candidates for bioweapons research. Afterwards, no major changes

observed.

>>>Start with 4 Leeches<<<

February 10th, 1978.

- 7 days since the adminstration of the "T". Rapid growth to double former size, signs

of tranformation emerging. Spawning successful, they double their numbers in an hour,

but their ravenous appetites lead them to cannibalism. Hastened to incease food supply,

but lost 2.

>>>Doubled in numbers, now 8 leeches<<<

>>>Lost 2 to cannibalism, now 6 Leeches<<<

March 7th, 1978.

- Provided them with live feed, but lost half when the live food fought back. However,

the leeches are learning from experience, and are beginning to exhibit group attack

behavior. They are also ceasing cannibalism. Their evolution is exceeding expectations.

>>>No mention of increased number or of breeding, but they lose half their number so total leeches is now 3!<<<

April 22nd, 1978.

- The leeches no longer exhibit individual behavior, even when not feeding, they move as

a collective. They consume everything I offer with remarkable efficiency.

>>>Nothing happens<<<

- April 30th,1978.

An employee has stumbled onto my experiments. Can a human be a food source? How will the

leeches respond?

>>>Nothing Happens<<<

June 3rd,1978

- A day worthy of commemoration. Today they began to mimic me! Surely they recognize

their father.. Wonderful children, No one will take you away..

>>>Nothing Happens<<<

So the totals, in order 4 8 6 3

Is the combination!

(It's always easier to work backwards)