00:01
Ok, we are told the length of pregnancy follows a normal distribution.
00:06
That's the usual bell -shaped curve.
00:10
So along here is time in months.
00:12
What we get is that.
00:16
The mean in the middle here, every time, 2, 6, 8 days.
00:23
And with a normal curve, there are three numbers you have to know.
00:27
It's called the empirical numbers, and they are 65, 68, 95, and 99 .7.
00:40
Those numbers memorize.
00:43
The first one is simply the amount of data within one standard deviation of the mean.
00:50
In other words, one of 14 above, 14 below.
00:54
If i go 14 above 2, 6, 8, i'm going to get 2, 8, 2.
01:01
If i go 14 below, i get 2, 5, 4.
01:07
So that area there is 68 % of the data.
01:13
Now, what i want though is 95 % of the data...