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### Author Topic: Math Question  (Read 1953 times)

#### Jerrymac

• Galactic Bee
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##### Math Question
« on: May 02, 2006, 08:34:52 PM »
If I got this figured right, and say it right, see what answer you get.

On a planet far far away, there are twenty couples of exact same age to the minute. (That's just the way things happen on this planet OK!!!)

When they turn twenty years old all of them at the same time pop out a set of twins. One boy and one girl.

When these children turn 19 years old they get married. When they turn twenty, all of them at the same moment, they have a set of twins, one boy one girl. So is the way of this species.

So it is repeated with all offspring

This is all the kids each couple have.

Also on this planet these people (or creatures if you wish) die right when they turn 60 years old.

The question is, how many will populate this planet in 100 years?

How many in two hundred years.

And how many in three hundred years.

Hope I got that all correct.
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#### randydrivesabus

• Queen Bee
• Posts: 1072
##### Math Question
« Reply #1 on: May 03, 2006, 06:31:30 AM »
without actually running the numbers it looks like zero population growth.

#### beemaster

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##### Math Question
« Reply #2 on: May 03, 2006, 11:48:20 AM »
I too haven't ran the numbers - the simple conclusions people would think is a massive number, but I'm just guessing at year 100 there are probably similar numbers to the second or third generation and down from there until nothing by the third century. Just guessing...

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#### indypartridge

• Queen Bee
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##### Math Question
« Reply #3 on: May 03, 2006, 01:30:40 PM »
Assuming that in Year Zero  we start with the original 20 couples at age 0,
then:

Pop. at Year  0:  40 (gen1) = 40
Pop. at Year 20: 40 (gen1) + 40 (gen2) = 80
Pop. at Year 40: 40 (gen1) + 40 (gen2) + 40 (gen3) = 120
Pop. at Year 60:   0 (gen1) + 40 (gen2) + 40 (gen3) + 40 (gen4) = 120
Pop. at Year 80:  120
Pop. at Year 100: 120
Pop. at Year 200: 120
Pop. at Year 300: 120

If there's any premature death due to disease, wars, murder, accidents, whatever, then the population will not be able to sustain itself.

#### Jerrymac

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##### Math Question
« Reply #4 on: May 03, 2006, 02:35:37 PM »
OK you guys are too smart. You wouldn't believe how many only count 20 for first generation, and get extras out of the air to mate with the preceding generations.
:rainbowflower:  Light travels faster than sound. This is why some people appear bright until you hear them speak.   :rainbowflower:

:jerry: