00:01
Our confidence interval formula, we're gonna have our mean, plus and minus z times the standard deviation over square root of n.
00:29
Okay, so it took me a second to figure out what this is saying.
00:32
So i think x equals 13 .7, that's our sample mean, plus minus, we're trying to find, i'm sorry, i totally wrote z, but i meant t because it says to use a t distribution.
00:50
So we're gonna use t, and our confidence level is 0 .9, and then also our degrees of freedom are gonna be 18.
01:00
So you just need a t table for this.
01:02
So you're gonna have to look at, you're gonna first look at the degrees of freedom again.
01:07
It's gonna be 18.
01:08
You're gonna go across, and you're looking for alpha to be 0 .1.
01:16
But since this is gonna be two -tailed, it's either like alpha is 0 .1, or in two -tails, alpha is gonna be 0 .9.
01:28
Zero, five.
01:30
So i'm looking for alpha being 0 .05 for two -tails, and i'm also going down to the column, to the row where we have 18 degrees of freedom.
01:42
I get 2 .101.
01:43
That's just on the chart...