00:01
For this question, we want to test whether a population mean is different from 7 .5.
00:08
We're asked to test at a significance level of 0 .05.
00:12
To do so, we have a sample of 45, which yielded a sample mean of 7 .4, and a sample standard deviation of 1.
00:23
For this situation, the null hypothesis would be that the population mean is 7 .5, and the alternative hypothesis is that the mean is different from 7 .5.
00:41
Hypotheses are always about a population parameter.
00:47
Then we calculate the test statistic.
00:50
Since we don't know the population standard deviation, we must make use of the sample standard deviation.
00:56
Therefore, our test statistic is based on the t -distribution with n -1, or 44 degrees of freedom.
01:03
It's calculated as the sample mean minus the null hypothesized mean, divided by the sample standard deviation, over the square root of the sample size...