00:01
Hi, i'm david and i'm hitching.
00:02
Have you answered your question? now let me bring up your question here.
00:06
In the question here, we are going to discuss about the confidence interval for the mean.
00:12
Let me remind you that the competent interval for the m will be the x bar plus or minus zan4 over 2 times when the sigma of the square of the n.
00:21
There's another formula that will help us to find the sample size needed for the confidence interval.
00:27
The n will equal to the zn4 over 2, time when the sigma divide, by the margin of the error totally square.
00:34
In this question here, we are given the standard division sigma equal to the 3 .6.
00:41
The sample size n equals to 120.
00:44
The x bar equal to the 16 .2.
00:49
And in the question a, asked you find the 92 % confidence interval.
00:55
Now look at the formula, we have given the x bar and the sigma and the n.
00:58
The only quantity we don't know will be the z and 4 over 2.
01:03
Now at the 92 % confidence and 5 equal to the 8 % divided by 2 equal to the 4 % which is equal to the 0104.
01:13
Now to find this value i need to bring up the z table.
01:16
Let me copy the z table and then put the table on the right here.
01:24
Notice that the table i bring here it has the negative g score with the problem on the left tail...