topic Re: Challenge #123: When will Rabbits Rule the World? in Weekly Challenges

Challenge #123: When will Rabbits Rule the World?

JoeM — Tue, 13 Sep 2022 14:17:11 GMT

This one has been on my whiteboard for awhile and I've been meaning to publish this challenge. This weekly challenge should be a fun one! The question we are trying to answer is: In what future month/year will a new breed of rabbits to exceed the human population 2:1?

Let's set some rules for how this new breed of rabbit populates so we can try to find the day our civilization will be be under the rule of our new-found long-eared overlords.

1) We will start with 1 female and 1 male rabbit born today (0 months old)
2) Each month, each female produces a litter of 4 bunnies: 1 male and 3 females
3) A female cannot start to reproduce until she has matured to 4 months of age
4) All rabbits live only to 24 months in age. (Alive months 0-23, they cease to live at the start of the 24th month)

5) Don't forget human population grows too! Assume a 0.058% month over month human population growth!

I have provided an answer, but there may be little monthly nuances that account for slightly different answers. Sound-off on when you found out it is going to happen!

Re: Challenge #123: When will Rabbits Rule the World?

patrick_digan — Mon, 02 Jul 2018 17:37:59 GMT

I went for an iterative macro. It only took 41 iterations.
Workflow:

Macro:

Re: Challenge #123: When will Rabbits Rule the World?

TerryT — Mon, 02 Jul 2018 20:44:55 GMT

I got the same month, but my numbers don't match exactly!

Re: Challenge #123: When will Rabbits Rule the World?

CharlieS — Mon, 02 Jul 2018 20:55:34 GMT

I got the same date, but slightly different population counts for humans and the Supreme Overlords. Maybe this is close enough to count like in horseshoes and Holy Hand Grenades.

785,514,304 long-eared overlords and 336,183,913 humans

Re: Challenge #123: When will Rabbits Rule the World?

NicoleJohnson — Mon, 02 Jul 2018 21:18:35 GMT

Slightly different human population for my final result, with 24 extra humans - which frankly, in this terrifying scenario, I will gladly take.

Thanks for the super fun challenge, @JoeM! I can see why you were so excited for this one :) Now, off to go pull anything that looks like a carrot out of my garden, just in case...

Cheers,

Re: Challenge #123: When will Rabbits Rule the World?

terry10 — Tue, 03 Jul 2018 00:08:47 GMT

Averting my eyes from the GIF, I didn't notice the 2:1 population threshold and spent way too much time trying to find the error in my workflow. :(

Re: Challenge #123: When will Rabbits Rule the World?

mmongeon — Tue, 03 Jul 2018 17:45:24 GMT

Here's my solution.

Like many of the other submissions, I don't have the exact same population numbers, but I end up on the same month.

Main workflow:

Iterative macro:

Re: Challenge #123: When will Rabbits Rule the World?

patrick_digan — Tue, 03 Jul 2018 17:56:22 GMT

@mmongeon Your solution truly made my day! 51 formulas in one formula tool!

Re: Challenge #123: When will Rabbits Rule the World?

Ladarthure — Tue, 03 Jul 2018 18:28:54 GMT

Was very funny and made me learn how to use the iterative macro, thank's to @patrick_digan for the first answer and showing a way to do this macro (was planning to use multi_rows formula...

Re: Challenge #123: When will Rabbits Rule the World?

ggruccio — Tue, 03 Jul 2018 19:11:28 GMT

Going to see iterations of rabbits in my sleep!

Re: Challenge #123: When will Rabbits Rule the World?

danrh — Tue, 03 Jul 2018 19:28:53 GMT

I hate to be Johnny Raincloud, but while I got to the provided date, I wonder if it might actually be 7 months sooner ...

The difference is when a rabbit starts reproducing ( > 4 months or >= 4 months). Reading through the problem, it sounds like >= 4 months ...

Please correct me if I'm wrong. I'd appreciate every extra day I can get.

Re: Challenge #123: When will Rabbits Rule the World?

mmongeon — Tue, 03 Jul 2018 23:37:38 GMT

@patrick_digan

Ha ha, yeah, I know, it looks neat and tidy on the outside but there's a hidden jackhammer in the Formula tool! :)

Re: Challenge #123: When will Rabbits Rule the World?

mmongeon — Wed, 04 Jul 2018 00:16:14 GMT

@danrh

I had the same kind of problem, I had to interpret the assignment as if female rabbits start reproducing at 4 months but give birth the next month, so (> 4) and not (>= 4).

This is how I was able to get the right month, but I was still a little off on the exact population number, so there may be more to it than that.

Re: Challenge #123: When will Rabbits Rule the World?

ggruccio — Wed, 04 Jul 2018 03:41:31 GMT

@danrh and @mmongeon

Glad you guys spoke up!

This had me puzzled a bit as well. I solved it by interpreting it as though the comparison took place at the beginning of the month and any babies that were born during the month could not be counted until the start of the next month....which may be another way to get to the solution you both got to...

Re: Challenge #123: When will Rabbits Rule the World?

mmongeon — Wed, 04 Jul 2018 13:07:33 GMT

Here's a second solution.

"Look Ma, no Iterative Macros!"
Getting creative... putting the male and female rabbit population in a single column so I can calculate and store the 2 values with a single Multi-Row Formula tool.

Re: Challenge #123: When will Rabbits Rule the World?

Ukashi — Wed, 04 Jul 2018 13:20:49 GMT

Hi @patrick_digan

you have me puzzeled, you mentioned 41 iteration but how with that number of iteration you end up on date 2022-08-02 shouldn't that date mean something like 48 iterations (it is 4 years from starting date) , or alternatively with 41 iteration shouldn't you end around 2022-01-02?

Re: Challenge #123: When will Rabbits Rule the World?

Ukashi — Wed, 04 Jul 2018 13:37:03 GMT

Hello,

That is a fun challenge :)

I was struggling a bit with my results bit thanks to @danrh I got back on track becouse I was afraid that bunnycalypse will come 7 month earlier :)

Re: Challenge #123: When will Rabbits Rule the World?

patrick_digan — Wed, 04 Jul 2018 14:48:28 GMT

@Ukashi good catch. I did land on 48 iterations for my final version. The 41 iterations was when I let the bunnies reproduce a month earlier. I changed it to match the solution provided.

Re: Challenge #123: When will Rabbits Rule the World?

Ukashi — Wed, 04 Jul 2018 14:51:43 GMT

Thanks for that @patrick_digan - I've paid attention as I've come across the same thing and initially could not find where the problem is :)

Re: Challenge #123: When will Rabbits Rule the World?

philipmannering — Wed, 04 Jul 2018 15:26:18 GMT

I'm baking my noodle over this one. Couldn't get the right month. Like @Ukashi it takes my macro between 41 and 42 iterations which works out as 2022-01-22.

Had to keep all rows to keep track of the age of the bunny (as they will give birth and die at different times).