00:01
In this question, the sample mean given as for the first one, which is 70, and the sample mean for the first one that was given as, which is 140, this is 140, and the standard deviation, so the standard deviation given as 10 here, and the confidence level, which was given as 95%, we can write as 0 .95, so we have to calculate the confidence interval for the population mean.
00:25
First of all, remember the formula, the confidence interval for the population mean, this is sample mean, plus or minus, because we know the sample standard deviation, use the t distribution, sample standard deviation, divided by root n.
00:37
Let's get the t value first.
00:39
So the alpha is 1 minus confidence level, we need alpha over 2, this is 1 minus 0 .95, divided by 2, which would be 0 .025, and also i need the degrees of freedom n minus 1 here, so this is 7 to minus 1, which is 69...