00:01
So the question here is asking about the endpoints of confidence intervals for different levels of confidence for sample proportions.
00:09
So we had a sample proportion of 0 .66 for the percent of senior financial professionals that believe that global warming is having the significant impact on the environment.
00:25
Part b asks for an 80 percent confidence interval, so we'll just fill stuff in here.
00:30
If i want an 80 % confidence interval, the z crit for that is 1 .28.
00:37
And that can just be found in a table of z criticals.
00:41
That's the 80 % z crit.
00:44
And then fill in the p hat and the sample size of 100 here.
00:54
And to three decimals so that we can have one after converting back to a percent.
01:01
We would have 0 .592 .721.
01:09
So this would be 59, between 59 .9.
01:13
And 72 .1%.
01:17
Those would be the endpoints of the interval for the 80 % confidence interval.
01:22
Part c asks you to do a 97 % confidence interval.
01:25
So it's the same calculation, but you need the 97 % z critical value...