00:01
So in item a, we should give an estimate of the estimator for the mean here.
00:09
So basically, the estimate for the population mean is the simple mean.
00:15
So what we need to do is sum this observation, this 15 observations that we have, and divide this sum by 15.
00:22
And we are going to get that the mean is 148, 47.
00:26
7.
00:28
We can now find for the item b what is the sample standard deviation, because we need this to compute the confidence interval.
00:38
So this sample standard deviation will be the sum for all the observations that we have, which is 15.
00:44
And we need to take each value that we have, subtract the mean, compute the square of this difference for each observation, then sum these squares, and divide this by the number of derivations minus 1, 14, and then take the square root.
01:02
So this will give us that the s here is 02022.
01:10
So with this information, we can find the confidence interval as the sample mean, plus and minus a t value times the sample standard deviation divided by the square root of n.
01:25
So this t value here is because the sample size is small and we also don't know the value.
01:32
Of the standard deviation in the population.
01:36
So we can say that is unknown.
01:39
So that's why that we have to compute using the sample.
01:42
So because of this, we are going to use the t student distribution here.
01:49
And this t student distribution has degrees of freedom equals to the sample size minus 1, which is 14.
01:56
And for a 98 % confidence interval, the area left to this number is 0 .99.
02:03
So if you use the t -table with these degrees of freedom, you're going to get that this value here is 2 .62 .45...