Step by Step process of solving Logic sums

CAT Exam
At heart, logic games are about how to organize or categorize certain information. You’re given some rules (also known as constraints) and you have to figure out what organization is allowed—or, perhaps, what organization is prohibited—based on those rules. Before we start, try out this problem: “*A literature department at a small university in an English-speaking country is organizing a two-day festival in which it will highlight the works of ten writers who have been the subjects of recent scholarly work by the faculty. Five writers will be featured each day. To reflect the department’s strengths, the majority of writers scheduled for one of the days will be writers whose primary writing language is not English. On the other day of the festival, at least four of the writers will be women. Neither day should have more than two writers from the same country. Departmental members have already agreed on a schedule for eight of the writers. That schedule showing names, along with each writer’s primary writing language and country of origin, is shown.
  • “Day 1:
Achebe (male, English, Nigeria) Weil (female, French, France) Gavalda (female, French, France) Barrett Browning (female, English, UK)
  • “Day 2:
Rowling (female, English, UK) Austen (female, English, UK) Ocantos (Male, Spanish, Argentina) Lu Xun (male, Chinese, China) “Select a writer who could be added to the schedule for either day. Then select a writer who could be added to the schedule for neither day. Make only two selections, one in each column.” Manhattan Prep GMAT Blog - Know the GMAT Code: Logic Games in Integrated Reasoning by Stacey Koprince     1-second Glance. There’s a lot of information for 3-ish minutes! So think carefully about how you’re going to Read and Jot on this one. First, the Day 1 and Day 2 lists pop out visually, even before you read anything. These lists don’t absolutely guarantee a logic game, but they’re a likely signal—so you would already be thinking, “Okay, is this a logic game?” before you even start reading. That’s important because the key to logic games is making sure you note and understand all of the rules or constraints. That’s going to be your focus—don’t copy down the lists themselves. Read and Jot. Here we go. Two-day festival. Ten writers, five per day.   As you jot that stuff down, you will realize that you don’t know which day is the “non-English” day and which day is the “women” day. Underline the word “other” to help you remember that. Reflect and Organize. Even though you are not done reading everything, there’s so much info here that you may want to pause to think about what you want to do next. You’ve got the rules. Since 8 of the 10 writers are already set, they’re presumably going to ask you to figure out some possibilities for the other 2. So you don’t want to just passively read through the lists—that’d be a waste of time. At this point, glance all the way down to the question itself. What do they want us to do? We’ve got to figure something out about the two unknown writers. Specifically, we’ve got to find someone who could fit either day, and then we’ve got to find someone who can’t be selected at all. Solve. Okay, back to the Day 1 and Day 2 lists. Let’s start with that thing we know we don’t know: Which day is non-English and which day is women? Start first with the most constraining factor—the one that gives you the least wiggle room. (This is a good principle on all logic games.) In this case, the most constrained day is “women”—that day has to have 4 or 5 female writers. Glance down the genders listed for each day. Day 1 does have three females already, so that one could go to four once we add one more person. Day 2, on the other hand, has two females and two males. Even if we add a female in the fifth slot, this day will have only three females—so this can’t be the “4+ females” day. Therefore, Day 1 is the “4+ women” day and Day 2 is the “3+ non-English” day. Reflect again.  Since Day 1 currently has only three women, we’ve got to choose another woman for that day. What about Day 2? At least three need to be “non-English” but currently only two are—so the person chosen for Day 2 has to write primarily in some language other than English. Therefore, the correct answer for the first column (someone who could go on either day) has to be a woman who writes in a language other than English. Look through the answers. Both M(urasaki) and C(olette) fit the bill. We must have to use some other rule to narrow down further. What haven’t we used yet? No more than two people from the same country! M is from Japan and C is from France. Check Day 1. There are already two people from France on Day 1. We can’t have a third, so C is out. The correct answer for the first column (Either) is Murasaki. Next one should go a bit faster because we actually understand all of the rules now. Murasaki can go on either day, so she can’t be the correct answer for Neither. That’s one down. What about the rest? We already figured out that C can’t go on day 1, so check her next for Day 2. Day 2 needs another non-English writer, but C qualifies for that. And C is from France—nobody else from France is scheduled on Day 2. So C could be on Day 2; she’s not the correct answer for the “Neither” column. What to check next? Day 1 requires a woman, so any of the men cannot go on Day 1. Check the men against the requirements for Day 2. Longfellow can’t go on Day 2 because we need another non-English writer. The correct answer for the first column (Neither) is Longfellow. You don’t need to check the other answer choices because you’ve found answers that work, but here’s the reasoning for all of the answers, just in case you want to check. LeGuin: Can go on Day 1. Can’t go on Day 2 (fails non-English rule). Longfellow: Can’t go on Day 1 (fails female rule). Can’t go on Day 2 (fails non-English rule). CORRECT answer for column 2 (Neither). Murasaki: Can go on Day 1. Can go on Day 2. CORRECT answer for column 1 (Either). Colette: Can’t go on Day 1 (fails max 2 per country rule). Can go on Day 2. Vargas Llosa: Can’t go on Day 1 (fails female rule). Can go on Day 2. Zola: Can’t go on Day 1 (fails female rule). Can go on Day 2.

Key Takeaways for Knowing the Code

(1) If you see a list (of things grouped together, as in this problem, or of rules), there’s a pretty good chance you’ve got a logic game. (2) People are often in the “love ‘em” or “hate ‘em” categories for logic games. If you love them, great. Jot down the rules, keep track of the logic carefully, and go for it. If you hate these, feel free move on. (3) Turn any knowledge you gain into Know the Code flash cards: Manhattan Prep GMAT Blog - Know the GMAT Code: Logic Games in Integrated Reasoning by Stacey Koprince

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