00:01
In this question, the confidence level was given as, which is 0 .95, and the sample mean was also given here, which is 16 .8, and also the population standard division that was given as 9 and the sample size, which is 60 here.
00:15
So we have to find the confidence interval for the population mean.
00:18
First of all, let's remember the formula, the confidence interval for the population mean.
00:22
This is sample mean, plus or minus.
00:24
Because we know the population standard division, use the z -distribution.
00:28
Population standard division divided by square root of n.
00:31
Let me get the z -value first.
00:32
So the alpha is 1 minus confidence level, but we need alpha over 2.
00:36
1 minus 0 .95 and divide by 2, which would be 0 .025 here.
00:41
In order to get the z -value, so i'm going to use the inverse norm function for this calculation.
00:49
So the mean and the standard division...