00:01
We have a random sample of size 33 with average wait time of 222 minutes with a sample standard deviation of 76.
00:16
And then we want confidence intervals for the mean waiting time, so that is going to be x bar plus or minus t with n minus 1 degrees of freedom and alpha over 2 in each tail times s over the square root of n.
00:52
And when we want a 90 percent confidence interval, that means that alpha is 10 percent and that we need t with 5 percent in the tail, so 0 .05, and we want 32 degrees of freedom, which is equal to, let's see here, we have 32 degrees of freedom, we have 5 percent in each tail, so that means that my t is 1 .694.
01:41
And when we have 95 percent, that means that alpha is 5 percent, so we need t with 0 .025 in the tail and 32 degrees of freedom, which is 2 .037.
02:06
And then if we want a 99 percent confidence interval, then our alpha is 1 percent, so we need t with 0 .005 in each tail.
02:20
We still have 32 degrees of freedom, so this value then is equal to, let's see here, 0 right tail, 2 .738...