A quality control manager wants to see how many defective products come off the line on average per day. They take 10 random units produced over the course of the day from each of 10 machines to test if they are defective. What type of sampling method is this?

Welcome back. For this problem, we have a quality control manager who wants to see how many defective products come off the line on average per day. They take 10 random units produced over the course of the day from each of the 10 machines to test if they are defective. We wanna know what type of sampling method is this. We can see that they were deliberately taking at least one unit from every machine. And if we think of each machine as a group, so the units produced by that machine would be in one group or strata, this is an example of a stratified sample because we are taking at least one unit from each of our groups. Great work.