00:01
Let me take note what values are given here.
00:03
The sample of 15, so the sample size is 15.
00:07
Confidence level was given as 80 percent, so we can write as 0 .80.
00:12
And the sample mean is also given, which is denoted by x bar.
00:15
This is 72 .8.
00:16
And also we have the sample standard division, which is 12 .9 here.
00:20
So what we have to find? we have to find the confidence interval for the population mean.
00:26
So because we know the sample standard division, so we have to use the t distribution.
00:32
So this is sample mean plus or minus t alpha over 2, sample standard division divided by square root of sample size.
00:38
This is the formula we need.
00:41
Let's get the t alpha over 2 value.
00:42
So the alpha is 1 minus confidence level...