00:01
So it looks like we are going to use the following information, that the x bar is equal to 36, the standard deviation is 7, and we have a sample size of 16 to calculate some confidence intervals for the population mean.
00:15
And the first one we want is a 90 % confidence interval.
00:19
So we're going to take our x -bar, plus or minus, and the z -value we'll use for 90 % is to use a 1 .645 times the population standard deviation over the square root of 16.
00:35
And so that is 36 minus 1 .645 times 7 divided by 4.
00:43
And let me double check and make sure that that's 1 .645.
00:47
So that's, that's me trying to go from memory and i could be a 1 .28.
00:53
So i'm going to just double check here.
00:56
Nope, it's 1 .645.
00:58
So i just want to double check.
01:00
All right.
01:01
So the low point for that is 33 .121 and it would round to to 3 on my calculator and then changing that into an addition sign.
01:15
Well, it helps if i change it to an addition sign.
01:19
There we go...