00:01
For this question, the confidence level, which is given as 95%, is a decimal number we can write as 0 .95, and the proportion given here, which is 0 .9, and the sample size, which is 169.
00:13
So we're going to find the margin of error.
00:16
Let me first of all remember the formula.
00:18
So the margin of error for this distribution, which is z alpha over 2, this is squared of p times 1 minus p and divided by n.
00:26
Let's get the z value first.
00:27
So the alpha is 1 minus confidence level, but we need alpha over 2.
00:31
This is 1 minus 0 .9 divided by 2, which would be 0 .05.
00:36
To get the z alpha over 2, i'm going to use the graphing list when i calculate the replication inverse norm.
00:41
So the area was 0 .05.
00:43
So for the standard normal distribution, the mean is 0, and the standard division is 1.
00:48
Press second, variance, the inverse norm, this is 0 .05.
00:51
And then, sorry, this is 0 .95.
00:57
Sorry, my bad...