00:01
We want to know a particular t value.
00:03
I'll start by drawing a t distribution.
00:06
The total area under this curve is 1, or 100%, and it is symmetric.
00:12
Its mean is 0.
00:13
It's a lot like the standard normal curve, except the tails are wider.
00:17
The fewer the degrees of freedom, the wider the tails are.
00:21
And when we say we want t to construct a 95 % confidence interval, we're saying that if you make an interval from t down to minus t, 95 % of this curve will be in your interval.
00:34
What does t have to be to make that happen? so you need the degrees of freedom to know the shape of the curve, and that's n minus 1.
00:43
We have a sample size of 27, so that would be 26.
00:47
We also need alpha...