So pause this video and see if you can figure this out on your own. All right, well I always just like to remind ourselves what's going on here before I just go ahead and calculate the p-value. So there's some data set, some population here, and the null hypothesis is that the true mean is 18. The alternative is that it's less than 18. So to test that null hypothesis, Miriam takes a sample. Sample size is equal to seven. From that, she would calculate her sample mean and her sample standard deviation.