00:02
We're going to construct a 90 % confidence interval to estimate the average number of days americans go to work out at a fitness center.
00:11
Now, because this data is quantitative, we're going to be using the t distribution.
00:16
And for our confidence interval, this formula, where x bar is the sample mean, which is 3 .4.
00:27
The sample standard deviation s is 2 .9.
00:33
And the sample size n is 240.
00:38
And then for our critical value, we've got to go to the t distribution critical value table and look up a degrees of freedom of 240, takeaway one, which would be 239, but there's not that on the chart, so we're going to go down to degrees of freedom of 100.
00:56
And at 98 % confidence, degrees of freedom 100, t -star is 2 .364...