The thing that we've been doing from the get go is estimating that character with our sample standard deviation. So we've been estimating the true standard deviation of the population with our sample standard deviation. Now, in this problem, this exact problem, we're going to run into a problem. We're estimating our standard deviation with an n of only 7. So this is probably going to be a not so good estimate. Let me just write, because n is small. In general, this is considered a bad estimate if n is less than 30.