00:01
So for this problem, we are looking for a 95 % confidence interval for a proportion.
00:06
Now, the formula that we'll use here is that this is going to be p -hat, our sample proportion, plus or minus, our critical z value, times the square root of our sample proportion times one minus the sample proportion, divided by our sample size.
00:22
Now, i'll note, since we have that this is going to be a 95 % confidence level, we want our critical z value to be z for a proportion of 0 .025.
00:32
So that's going to give us a result of 1 .96.
00:35
We have that our sample proportion value, p hat, is going to be equal to 235 divided by 1 ,700, which gives a result of about 0 .138.
00:50
So the confidence interval then is going to be given by 0 .138 plus or minus 1 .96 times the square root of 0 .138 times 1 minus 0 .138 divided by 1 ,700.
01:12
Evaluating that out, we'll find that the lower end of the confidence interval is going to be 0 .122, and the upper end of the confidence interval is 0 .15...