00:01
For this problem, we are asked to give the best point estimate for p, the margin of error, and the 99 % confidence interval for the proportion who will answer yes to a question, given that 62 answered yes in a random sample of 90 people.
00:15
So, p is approximately going to be our p hat value, our sample proportion, 62 over 90, which equals 0 .689.
00:26
So i'll round that to 0 .689.
00:32
Then our margin of error, let's see here, oh, i had a formula on screen.
00:38
Our margin of error is equal to, i'll just scribble it down, z star for the appropriate confidence level, times p hat, or times the square root of p hat times 1 minus p hat divided by n.
00:54
So for our 99 % confidence, and i'm just using stat key here, we'll find that our z star value is 2 .576, then we multiply by the square root of 0 .689 times 1 minus 0 .689 divided by 90...