The corporate world is full of \u201cyes men\u201d and \u201cgroupthink\u201d \u2013 of the kind of inertia that leads companies to think in the same direction without considering alternate points of view.\u00a0 To combat that, employers and business schools seek those who can see the entire array of possibility, and the GMAT tests for that in many Data Sufficiency problems.\u00a0 Consider a problem like:<\/p>\n
Is the product jkmn = 1?<\/p>\n
(1) jk\/mn = 1<\/p>\n
(2) j, k, m, and n are integers<\/p>\n
Considering statement 1 it is easy to get the answer \u201cNO\u201d.\u00a0 Using 1, 8, 2, and 4, for example, satisfies statement 1\u2032s constraints but clearly gives a product unequal to 1.\u00a0 So does 1, 20, 5, and 4.\u00a0 But having just one \u201cNO\u201d should immediately change your focus toward getting the other answer.\u00a0 A series of nos using similar numbers (1, the product of two integers, and those two integers is the formula we used to create both options thus far) doesn\u2019t do you any good.\u00a0 You need to either prove that the statement is sufficient in all cases or find the case or two that doesn\u2019t give the same answer, rendering the statement insufficient.\u00a0 And in either case you need to try different types of numbers.\u00a0 With that as your guide, you might be persuaded to try nonintegers as at least a few values:\u00a0 1\/2, 2, 1\/4, 4 satisfies statement 1, but also provides the product 1 and the answer \u201cYES\u201d.\u00a0 We can prove the statement insufficient using these not-as-obvious nonintegers, and that\u2019s why having a goal of insufficiency is so helpful: it forces you to try unique numbers.<\/p>\n
Statement 2, however, renders our noninteger choices obsolete.\u00a0 We can use the same integers as before (1, 8, 4, 2) t o get \u201cYES\u201d, but now we need to try harder to get \u201cNO\u201d as the fractions don\u2019t work.\u00a0 Here, again, the key to unlocking this one may be in our goal: we want the statement to be insufficient!\u00a0 So we should push the limits of possibility. Does the statement say that we can\u2019t repeat numbers?\u00a0 No!\u00a0 So we can say that j, k, m, and n are 1, 1, 1, and 1, rendering both statement 2 and both statements together insufficient.\u00a0\u00a0 A major component of Data Sufficiency is that it rewards you for playing devil\u2019s advocate \u2013 for noting the few unique cases in which a likely conclusion is invalid.\u00a0 By making that your goal, you can ensure that you\u2019re working toward those unique case numbers (like negatives, fractions, primes, 0) that tend to produce different results.<\/p>\n
2) Beware of the Obvious Answer<\/strong> What is the value of x?<\/p>\n 1)\u00a0\u00a0\u00a0\u00a0\u00a0 3x + 2y = 15<\/p>\n 2)\u00a0\u00a0\u00a0\u00a0\u00a0 y = (-3\/2) (x \u2013 5)<\/p>\n This should pretty obviously be C.\u00a0 Two equations, two variables, neither works alone but both work together, right?\u00a0 But that is too easy, and the GMAT won\u2019t often give you the answer that quickly.\u00a0 Much as though the author had moved a pawn to expose her rook in a chess match to bait you into giving up your queen, you should take this situation to make sure that the author isn\u2019t luring you into an easy trap.\u00a0 With that as your motivation to rearrange the algebra, you will notice that statement 2 is exactly the same relationship as statement 1:<\/p>\n y = (-3\/2) (x-5)<\/p>\n 2y = -3(x \u2013 5)<\/p>\n 2y = -3x + 15<\/p>\n 2y + 3x = 15<\/p>\n While you may not see this right off the bat, the relative ease with which choice C comes to you should be your guide \u2013\u00a0 do not\u00a0 accept an easy answer without digging into the statements a little further to further investigate.<\/p>\n 3) Do Not\u00a0 Contradict Yourself<\/strong> Consider the question:<\/p>\n Is x < 0?<\/p>\n 1) x^2 = 9x<\/p>\n 2) The absolute value of x = -x<\/p>\n Did you get x = 9 for statement 1, meaning a definitive NO?\u00a0 And x is negative for statement 2 for a definitive YES?\u00a0 Most do.\u00a0 But how can x be both \u201cnegative\u201d and \u201c9\u2033 at the same time?\u00a0 Clearly, as these statements contradict each other, we messed up the math somehow.\u00a0 What did we\u00a0 forget?\u00a0 In both cases, x could be 0.\u00a0 In statement 1 that still gives us \u201cNO\u201d but in statement 2 that gives us an insufficient.\u00a0 So the answer is A, not D as many might think.\u00a0 And it was recognizing this inconsistency with both statements \u2013 remember, statements are facts\u2026they must be true! \u2013 allowed us to catch that potential mistake.<\/p>\n Ready to sign up for a GMAT course ? Enroll through GMAT Club and save up to $180 (use discount code GMATC10)! Take a look at our course options in some of our most popular cities: New York<\/a>, Chicago <\/a>and Los Angeles<\/a> and make sure to check the Veritas Prep blog<\/a> for daily articles.<\/p>\n","protected":false},"excerpt":{"rendered":" Perhaps no GMAT item is as emblematic of the test as is a Data Sufficiency question.\u00a0 It is\u00a0 unique to the GMAT and true to the aims of this specific…<\/p>\n","protected":false},"author":101,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[718,736],"tags":[],"class_list":["post-8259","post","type-post","status-publish","format-standard","hentry","category-data-sufficiency-gmat","category-quant-gmat","entry"],"aioseo_notices":[],"_links":{"self":[{"href":"https:\/\/gmatclub.com\/blog\/wp-json\/wp\/v2\/posts\/8259","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/gmatclub.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/gmatclub.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/gmatclub.com\/blog\/wp-json\/wp\/v2\/users\/101"}],"replies":[{"embeddable":true,"href":"https:\/\/gmatclub.com\/blog\/wp-json\/wp\/v2\/comments?post=8259"}],"version-history":[{"count":2,"href":"https:\/\/gmatclub.com\/blog\/wp-json\/wp\/v2\/posts\/8259\/revisions"}],"predecessor-version":[{"id":8261,"href":"https:\/\/gmatclub.com\/blog\/wp-json\/wp\/v2\/posts\/8259\/revisions\/8261"}],"wp:attachment":[{"href":"https:\/\/gmatclub.com\/blog\/wp-json\/wp\/v2\/media?parent=8259"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/gmatclub.com\/blog\/wp-json\/wp\/v2\/categories?post=8259"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/gmatclub.com\/blog\/wp-json\/wp\/v2\/tags?post=8259"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}
\nData Sufficiency questions are supposed to be hard; more so than any other question type they tend to represent a chess match between you and the author, as the author has two chances to get you to make a mistake.\u00a0 She won\u2019t likely waste either statement giving you an easy pass \u2013 the questions have to elicit something from you in terms of efficiency or ingenuity in order to answer them correctly, so if an answer choice seems obvious within 15-20 seconds and you cannot spot a trap, well, you just fell into the trap.\u00a0 Consider the question:<\/p>\n
\nThere is\u00a0 a hard-and-fast rule regarding Data Sufficiency that people don\u2019t know and use as much as they should: the statements can never contradict each other.\u00a0 Knowing this, if your answers for statement 1 and statement 2 are different, you must go back and reconsider your math; as Boston GMAT tutor David says, that\u2019s an \u201canswer choice F\u201d, meaning that you just effed up the math somehow.<\/p>\n![\"\"](\"..\/wp-content\/uploads\/2011\/06\/Veritas-New-Logo1.jpg\" "\\"Veritas"){kind=logo}
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