00:01
In this question, the confidence level, which is given as 90 percent as a decimal number, this is 0 .90, and the sample size, which is 546, and the mean, sample mean, 16 .8, and the population standard division, 13 .1, because the sample size is large enough here.
00:18
So we need to get the confidence interval for the population mean.
00:22
First of all, remember the formula, which is the sample mean, plus or minus, because we know the population standard division, we have to use the z distribution, and population standard division, divided by root n.
00:33
Let's get the z value first.
00:34
So the alpha is 1 minus confidence level, but i need alpha over 2, 1 minus 0 .90, and divide by 2, which is 0 .05.
00:42
To get the z value, i'm going to use the graphing display calculator application inverse norm.
00:46
So the area here is 0 .05, and the mean and the standard division for the standard normal distribution.
00:51
So press second variance, and the inverse norm, 0 .05, and the mean and standard division.
00:57
So the value is negative 1 .64 and 5...