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Current time:0:00Total duration:9:02

Mixed setup questions | Video lesson

Video transcript

- [Instructor] In this video, we're going to work on the questions from the mixed setup about volunteers demonstrating certain tasks. So, before you continue with this video; make sure that you watch that previous video. Now, I'm going to show you how to work through each problem to get to get to the answer quickly using the deductions we've made So, that you can move on with confidence without having to go over all of the wrong choices each time. That's really all you're going to have time for on test day, anyway. So, let's see how we can gain some time back from the work that we did up front. By the way, if you would like to try the questions on your own before I explain them to you; feel free to pause the video at any moment so that you can do that before I move to the explanation. Our first question is an overview question. It asks which one of the following is an acceptable list of the volunteers and the tasks each demonstrates in order from the first to the last demonstration. So, for these overview questions; it's a good idea to start with the rules and eliminate the choices that violate each rule. It tends to be a lot faster than going to the choices and seeing if each choice works. So, rule number one tells us that Frank demonstrates exactly one task before Gladys demonstrates any of the tasks. Looking at the choices, which choice can we eliminate? Choice B violates rule number one because we see Frank demonstrating two tasks before Gladys demonstrates any of her tasks. So, we get rid of choice B. Rule two: Frank performs neither the first nor the last demonstration. We can eliminate choice A. Here we see that Frank does perform the first demonstrations so that breaks rule number two. Rule three: Gladys demonstrates neither harvesting nor milling. Scanning the remaining choices, we can see that D violates this rule. D show us that Gladys does demonstrate harvesting; so we can rule this choice out. Four: Leslie demonstrates neither harvesting nor threshing. We're only left with two choices, and it doesn't look like either of them violates this rule. So, we can move on to the last rule, which tells us that milling is the next task demonstrated after threshing is demonstrated. We can eliminate choice E, which shows us that threshing is two tasks before milling. So, that leaves us with C as the answer; and we can circle it and move to the next question. All right, this question asks us which of the following must be true. It's a must-be-true question; it doesn't give us any new information to work with so that means that we can use our deductions. And, we should be able to save a lot of time given that we made so many deductions up front. Choice A says that Frank demonstrates harvesting. That's it! We can select this and move on on test day because that's how the deductions up front save us time later on. A must be true. We deduced that Frank must demonstrate harvesting, and maybe we don't even remember how we got to those deductions. But, that doesn't matter. The work that we do in our initial setup should pay off in the questions. This question asks: If Leslie performs the fourth demonstration, then harvesting could be the demonstration performed when? This questions asks us for what could be true given the new condition that Leslie is fourth. So, we can redraw a bare-bones version of our initial diagram and incorporate this new rule that Leslie is fourth. So, let's make deductions. If Leslie is fourth, then that means that both Leslies are now accounted for. We've got the one in first and now the one in fourth. That means that Frank has to be second so that he's before the first Gladys; and we can also determine that Gladys has to be sixth, since we already accounted for both Leslies. The other Gladys must be third since we can't have the two Franks in a row based on rule number one. And, that means that the other Frank must be fifth; Since harvesting is performed by Frank; that means that our answer is either going to be second or fifth. Obviously, both of them can't be listed in the choices; and so our answer is B. Harvesting could be the demonstration performed second. If Gladys demonstrates plowing immediately before Frank demonstrates threshing, which one of the following must be true? This is a must-be-true question, and we're given the new condition that Gladys demonstrates plowing right before Frank demonstrates threshing. The problem is that we don't know where in the order this takes place exactly. So, redrawing our original diagram isn't actually going to help us too much here. What we can do is start with a new rule and see if we can build it out from there. So, let's draw Gladys demonstrating plowing immediately before Frank demonstrates threshing; and we'll make deductions from here. So, here Frank does threshing; and we also know from our initial deductions that Frank definitely does harvesting at some point. So, in this question, we know both of Frank's tasks: harvesting and threshing. Now, we're given a rule about threshing here. We know that milling is right after threshing based on the last rule. So, we can draw that in and make our group bigger. What do we know about milling and who demonstrates milling? Rule three tells us that Gladys can't do milling so it has to be Frank or Leslie. But, we just determined that Frank's tasks are already set. So, in this question, Leslie does the milling. So far we've accounted for half of the tasks here, and they're all in this group. Let's see if we can integrate this a bit into what we know from our initial diagram. For example, we know that Frank has to demonstrate before Gladys ever does. So, Frank is some time earlier than this Gladys; and that's got to be the harvesting Frank. We also know that Leslie is first, no matter what. So, here's the Leslie before that Frank. Who are we missing? We're only missing the other Gladys now. Where can she go? Well, either she goes before this GFL group and is the first Gladys, or she's after the group and is the second Gladys. She can't go anywhere else without breaking the first rule or without breaking up the group that this question establishes. So, we're asked which one of the choices must be true. Choice A tells us that Frank demonstrates harvesting for the second demonstration. Stop right there! This has to be true. Let's select it on test day, move on to the next question, and save so much time. That's what deductions will do for us. This question asks: Which one of the following must be true? And, here's another gift: We should be able to find the answer quickly based on our deductions. Which one of the choices must be true without any new information, just given the rules of the setup? Well, think about the two deductions we made up front. We said that Frank does harvesting, for sure, and the other deduction was that Leslie demonstrates first. So, there's the answer with choice D. Imagine if we hadn't made those deductions up front. Imagine we had to test all of these choices by hand with our pencil to see if they could be false or had to be true. That would take forever. And, it's the approach that so many students take when they first start out with the LSAT, which is a completely normal approach to take without practice. But, with practice and discipline, you can save yourself a lot of that trial and error by setting yourself up with making deductions in the initial setup. Our answer here is choice D.