00:01
Okay, so i see that you need help with this question, and it says assume a sample is used to estimate the population mean.
00:07
Find a 99 % confidence interval for a sample size of 380 with a mean of 24 .5 and a standard deviation of 14 .2.
00:17
Enter your answers accurate to three decimal places.
00:22
So for a mean, the mean is 24 .5.
00:29
The standard deviation is 14 .2, and the sample size is 380, and we have a 99 % confidence interval.
00:45
And so the first thing that you have to do is you have to calculate your t score.
00:50
So you're going to do 1 minus 0 .99.
00:52
That's 0 .01.
00:53
1 minus 0 .01 divided by 2, and that is 0 .995.
01:02
And so t0 .995 with a degree of freedom of 379, and you're going to get a t score of 2 .5889.
01:19
So then you're going to take 24 .5 plus or minus 2 .589.
01:31
I'm just going to go out three decimal places, times 14 .2 divided by the square root of 380.
01:40
So you're going to get 24 .5 plus or minus 2 .589 times 0 .7284.
01:51
And so then you have 24 .5 plus or minus 1 .886.
01:58
So then i have 24 .5 minus 1 .886, and that's 22 .614.
02:08
And then adding them together, that would be 26 .386...