00:01
So we have a survey of 45 company employees that shows that the mean length of christmas vacation was five days.
00:11
And we can assume that the sample standard deviation is one day.
00:16
And then we want to construct a 95 % confidence interval for the population mean, as well as a 90 % confidence interval.
00:34
Well for the 95 % our alpha is 5%.
00:44
So we will need the t with 0 .025, or half of that, and n minus 1 degrees of freedom will be, let's see, degrees of freedom is n minus 1, which is 44.
00:59
So 44 degrees of freedom.
01:02
And for the second confidence interval, our alpha is 10%.
01:06
So we need t with half of 10%, 0 .05, and 44 degrees of freedom.
01:14
So we can look up these numbers before we make our confidence intervals...