00:02
All right, so a research institute poll asked respondents if they felt vulnerable identity theft.
00:07
And in a poll, there was a thousand seven respondents with 535, it said yes.
00:13
So use it 95 % comments interval to, you know, i assume estimate the true proportion of respondents who would say that they feel vulnerable identity theft based on this data.
00:26
So what we would do is we're essentially going to use the one sample, zero, the interval with the form p hat plus minus our critical value z star times our center deviation of our sample data which will be the square root of p hat times one minus p hat all over n usually you'll give you usually you're giving this formula in formula sheet or you know and you know textbooks or notes now in either case this just comes down to you know make sure you plug in the correct values and make and make sure you don't make any mistakes with their calculator.
01:07
So our p hat will be 535 or a thousand seven, we're a thousand seven.
01:25
We about we can round it at 0 .53 and our z star since we're told 95 % common interval it'll be 1 .96 because the z star value is basically the the z score in this case where there's 95 % in the middle and that means there's 2 .5 % of area to the left and right.
02:05
So this is you know this would be negative z star and positive z star and for that you're going to either use your use the probability table i like to use inverse norm and this is a very common one so you may remember off the top of your head i remember that's 1 .96 but we you just do the area to the left which would be you know 0 .25 or 0 .025 2 .5 % and you see you'll get negative 1 .96 for this one and this one will be 1 .96 doesn't matter which when you use because if you're doing a plus minus here so just make it one make it positive so z star will be 1 .96 and so our formula becomes 0 .53 plus minus 1 .96 times points 53, 1 minus 0 .53, which will be 0 .47, all over 1 ,007, because that's our n.
03:16
Be careful what the calculator work, and one handwork, so you still mistakes can happen.
03:22
But you should get 0 .53 plus minus when you do 1 .96 times all that, get one point, end up getting 0 .038...