00:01
Let me take note of the given values.
00:02
First of all, the sample size denoted by n.
00:04
This is given as 1200.
00:06
And the number of supporters given here is, which is 650.
00:11
So for part a, we're going to use the confidence level as 95 percent as the decimal number.
00:16
I can write at 0 .95.
00:18
So the first thing i'm going to find, which is the sample proportion.
00:21
So the sample proportion is denoted by p here, which is x over n.
00:25
So this is 650 divided by 1200.
00:28
Let's get this value.
00:29
This is 650 divided by 1200.
00:32
So the value would be, which is 0 .542.
00:36
And let me write the formula for the population proportion, which is the p value plus or minus.
00:42
This is z alpha over 2 squared of, this is p times 1 minus p and divided by n.
00:48
Let's get the z value first.
00:49
So the alpha is 1 minus confidence level, but we need alpha over 2, which is 1 minus 0 .95 and divide by 2 would be 0 .025.
00:58
To get the z alpha over 2, i'm going to put all these values on the calculator, inverse norm application.
01:05
So the area was 0 .025.
01:07
And also we have the mean for the standard normal distribution and the standard deviation here, 1.
01:12
Press second, variance, and the inverse norm.
01:16
This is 0 .025 and mean and standard deviation...