00:01
Let me take notes what values are given for this question here.
00:04
So, the margin of error given here, which is 0 .03, and the confidence level, which was given as 90%, so we can write that as 0 .90, and we're going to find the sample size.
00:18
So, for part a, we just have to use the prior estimation, which is p is equal to, this is 0 .32.
00:27
Let's get the sample size here.
00:29
So, we're going to use the margin of error formula.
00:32
For the proportion, the margin of error formula is equal to, which is p times, this is square root of 1 minus p, and divide by n here.
00:39
If i take the square of the both sides and leave the n alone, so we will have, this is z value, divided by margin of error, and then bracket square root, times p, and times 1 minus p.
00:51
Let's get the z value here.
00:52
So, the alpha is 1 minus confidence level.
00:55
What i need? i need alpha over 2, which is 1 minus 0 .90, and divide by 2, which would be 0 .05 here.
01:02
So, to get the z alpha over 2 value, so what i need, i'm going to use the graphing display calculator application inverse norm, so the area was 0 .05, and the mean and the standard deviation.
01:15
Press second variance and the inverse norm, this is 0 .05, and then the mean, sorry, this is the mean 0 and the standard deviation is 1.
01:25
So, the value is negative 1 .645 here...