00:01
We have some information here.
00:02
We have a sample size 50, so n is 50.
00:06
A sample mean x bar is 0 .65 and a margin of error e is 0 .04.
00:15
How do we get the 95 % confidence interval? so the formula for a confidence interval for the population mean is given as x bar plus and minus the margin of error.
00:30
So the margin of error is half of the width of the confidence interval.
00:34
This is the point estimate, our best guess for the population mean.
00:40
So we don't know much about this population, but we do know that a sample of size 50 was drawn from it and the sample mean was 0 .65.
00:49
So we expect 0 .65 to be pretty close to the population mean and the margin of error is based on the standard deviation of the population.
01:03
So for example margin of error might look like z sigma over root n, but we don't have sigma and we have no estimator for sigma either.
01:13
What we have is the error.
01:15
So i could write this as 0 .65 plus and minus 0 .04...