00:02
All right, so we have a really interesting model here.
00:05
There's a limit to how long people can live.
00:09
Saying life expectancy from age 65 has increased much more slowly than life expectancy from birth.
00:13
Well, it says more slowly, i added much.
00:16
At some point, those will be equal, and you can expect to live - and even if you live to 65, that doesn't mean you're going to - that doesn't mean you expect to live any longer than if you hadn't made it to 65, or before you got to 65, i suppose.
00:29
And that's just how long people expect to live in general.
00:33
Let's see, so i'm going to say the expectancy at birth, which i will represent as b.
00:43
So b of 1990, i'm going to call that r - or 1900, excuse me.
00:50
Life expectancy of birth was 46 years.
00:56
And - excuse me - 65, so i'm going to call that e for elderly.
01:05
At age 65 was 76 years.
01:12
All right, so if you're born, you expect to live to be about 46, but if you've made it 65, you expect to make it to 76.
01:18
In 2008, so that's 108 years later, b of 108 is 78 .1, and e of 108 is 83 .8.
01:33
So a baby can expect to live about 78 years, but if you make it to 65, you can expect to make it to just shy of 84.
01:40
In both cases, the increase of life expectancy has been linear, so we can find an equation for it.
01:47
If we have our first thing is b minus - we'll put it in point -slope form.
01:54
So y minus y zero, b minus b zero, 46, is equal to m.
02:02
Let's see, what's our m? it's our delta y.
02:04
78 .1 minus 46, divided by 108, is our delta x, times x minus x1 is zero.
02:14
So it just - that times x, which means that our life expectancy from birth as a function of x is equal to - let's see, what is that? 78 .1 minus 46, got that, divided by 108, 0 .01572.
02:39
0 .01572 times x plus 46.
02:47
So life expectancy from birth appears to go up at about 1 % - 1 .5 % of a year every year.
03:01
Not great, but we'll deal with it.
03:03
E minus 76 - i mean, this isn't a great figure...