How many donkeys ?

dxr346

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How many tortoises ?

If there is one tortoise and it has a litter of 3 tortoises in 25 years ( just once ), and each of it's litters have 3 tortoises each in 25 years ( just once ) and the sequence follows on, How many tortoises will be there in 500 years ? Lifespan per tortoise = 80 yrs.
 
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Hello,

First of all,
sorry if my English is bad, that because i am not from an English-speaking country.
But, i think you could understand what i say, because mathematics is universal. :smile:


Wow!, but what if they laid eggs not just once?
I have found out that there is a pattern if its not just once.

If there is no death, The population after every birth year (every 25 year) tend to be a 4 to the power of the birthyear (4^n). (25 years= 1 Birth Year)

evidence:
Code:
Population
Birth Year 0 : 1                                         = 1
Birth Year 1 : 1 + 1x3                                 = 4
Birth Year 2 : 1 + 1x3  +  3 + 3x3                  = 16

and so on, it continues and always creating the exact number of generation that incredibly making every birth year is a power from 4 (4^n)

why does this happening?
because it is does not the same as the case of dividing bacteria.

First, in this case the original(the mother) still exists as the new generation(the child) born, and does not divide.
So, the population is not a sequence of 1,3,9,27

Second, in this case the new generation also can create their next generation and the mother still can create a new generation, if they dont laid eggs just once, but they laid eggs until their death.
So, the population is not a sequence of 1,4,13,

but there is an exception for total population after the 4th birth year. (because the 1st generation died and doesnt laid eggs anymore)
So, the total population is less than 4^n

the solution is reducing 4^n by the death and imagining the actual generation sequencing after the mother is dead

so, im curious about it and start working on it on my notebook
it is a long doodling in my notebook until i find the solution function

4^n - (4^(n-3)) - (3(4^(n-4))(n-4)) = Total population for n>3
4^n = Total population for n<4

so that were the formulas for the total population if it always laid eggs until their death

Just curious about it, Thank You :)
 
Oh Thanks,

My formula goes wrong at the eighth birth year.
When i try using Excel i found a pattern that more accurate than my formula

Code:
Year                                                                                                          Total Population
[TABLE="width: 636"]
[TR]
[TD]0[/TD]
[TD]1[/TD]
[TD] [/TD]
[TD] [/TD]
[TD] [/TD]
[TD] [/TD]
[TD] [/TD]
[TD] [/TD]
[TD] [/TD]
[TD] [/TD]
[TD] [/TD]
[TD]1[/TD]
[/TR]
[TR]
[TD]1[/TD]
[TD]1[/TD]
[TD]3[/TD]
[TD] [/TD]
[TD] [/TD]
[TD] [/TD]
[TD] [/TD]
[TD] [/TD]
[TD] [/TD]
[TD] [/TD]
[TD] [/TD]
[TD]4[/TD]
[/TR]
[TR]
[TD]2[/TD]
[TD]1[/TD]
[TD]3[/TD]
[TD]12[/TD]
[TD] [/TD]
[TD] [/TD]
[TD] [/TD]
[TD] [/TD]
[TD] [/TD]
[TD] [/TD]
[TD] [/TD]
[TD]16[/TD]
[/TR]
[TR]
[TD]3[/TD]
[TD]1[/TD]
[TD]3[/TD]
[TD]12[/TD]
[TD]48[/TD]
[TD] [/TD]
[TD] [/TD]
[TD] [/TD]
[TD] [/TD]
[TD] [/TD]
[TD] [/TD]
[TD]64[/TD]
[/TR]
[TR]
[TD]4[/TD]
[TD][/TD]
[TD]3[/TD]
[TD]12[/TD]
[TD]48[/TD]
[TD]189[/TD]
[TD] [/TD]
[TD] [/TD]
[TD] [/TD]
[TD] [/TD]
[TD] [/TD]
[TD]252[/TD]
[/TR]
[TR]
[TD]5[/TD]
[TD] [/TD]
[TD] [/TD]
[TD]12[/TD]
[TD]48[/TD]
[TD]189[/TD]
[TD]747[/TD]
[TD] [/TD]
[TD] [/TD]
[TD] [/TD]
[TD] [/TD]
[TD]996[/TD]
[/TR]
[TR]
[TD]6[/TD]
[TD] [/TD]
[TD] [/TD]
[TD] [/TD]
[TD]48[/TD]
[TD]189[/TD]
[TD]747[/TD]
[TD]2952[/TD]
[TD] [/TD]
[TD] [/TD]
[TD] [/TD]
[TD]3936[/TD]
[/TR]
[TR]
[TD]7[/TD]
[TD] [/TD]
[TD] [/TD]
[TD] [/TD]
[TD] [/TD]
[TD]189[/TD]
[TD]747[/TD]
[TD]2952[/TD]
[TD]11664[/TD]
[TD] [/TD]
[TD] [/TD]
[TD]15552[/TD]
[/TR]
[TR]
[TD]8[/TD]
[TD] [/TD]
[TD] [/TD]
[TD] [/TD]
[TD] [/TD]
[TD] [/TD]
[TD]747[/TD]
[TD]2952[/TD]
[TD]11664[/TD]
[TD]46089[/TD]
[TD] [/TD]
[TD]61452[/TD]
[/TR]
[/TABLE]
 
25 years

Where are the donkeys :confused:

Following needs to be clarified:
1: by "just once", do you mean just once in 25 years, or just once in 80 years?
2: in what year will the 1st turtle die; will others die similarly?
3: any reason for using 80 years...as compared to 75 years?

---------

1 Just once per life time (80yrs) but all litter at 25 years.
2 All die at 80.
3 I used 80 yrs so that it tallies with human lifespan in general. Thought tortoises might be more interesting.
 
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Observation

So 1st turtle (year 0) somehow gets pregnant and has litter of 3 at year 25,
then lives happily after until it kicks the bucket at year 80.

The 3 born at year 25 each has litter of 3 at year 50:
so at year 50 we have 1 + 3 + 9 = 13, and turtle#1 then has 9 grand-turtles.

0: 1
25: 4 (who gets the cigars?) : the 3 born here will die at year 105***
50: 13
75: 40
80: 39 (1st turtle funeral)
100:120
105:117***

Take over, Mark McQuaid!

I am always interested in where I go wrong, so what is wrong with the following:

Each birthed tortoise delivers one and only one set of three offspring, none die before reproducing which means the population will increase geometrically, base 3. (This is effectively like ameba or dollars increasing exponentially.)

In year 500 the 500/25 = 20th generation is born and at that time there will be 3^20 new torti born.

The total population will be that number plus the last two generations since the 3rd last generation will join all fore-bearers and die with the birth of their grandchildren. Thus, the surviving population will be 3^20 + 3+^18. (with 80 instead of 75, the third from the last would still be alive so 3^20 + 3+^17).

Things would be much more complicated if the surviving parents continued to reproduce, or each child failed to join their cohort and reproduce.
 
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