{"id":7242,"date":"2019-09-02T03:09:52","date_gmt":"2019-09-02T08:09:52","guid":{"rendered":"http:\/\/www.kaptest.com\/blog\/business-school-insider\/?p=7242"},"modified":"2020-09-11T20:41:00","modified_gmt":"2020-09-11T20:41:00","slug":"land-score-mastering-data-sufficiency","status":"publish","type":"post","link":"https:\/\/wpapp.kaptest.com\/study\/gmat\/land-score-mastering-data-sufficiency\/","title":{"rendered":"Solving and Mastering Data Sufficiency Questions on the GMAT"},"content":{"rendered":"

Data Sufficiency must be <\/span>practiced<\/span> every day. It\u2019s like these questions use a part of your brain that is seldom employed for other purposes; much like a little-used muscle, you need to warm up and use it regularly or it won\u2019t work well when needed. The Critical Thinking skills tapped by Data Sufficiency require regular exercise.<\/span>
\nMerely understanding <\/span>how to solve Data Sufficiency problems<\/span><\/a> will not allow you to <\/span>actually<\/span><\/i> solve them, much like merely knowing the lyrics and melody of a song doesn\u2019t allow you to <\/span>perform<\/span><\/i> it. Thinking critically when faced with a timed practice problem on the screen requires performance, and the only way to properly perform the steps is to practice them.<\/span>
\nIt’s not enough to know and be comfortable with the Kaplan Methods. Instead, you need to work Data Sufficiency questions into your practice schedule. For example, you could work three questions each day. It doesn’t matter if you get them correct; the act of applying\u00a0your knowledge by practicing with test-like questions and then reviewing the full explanations gradually improves both\u00a0you confidence and accuracy.
\nThis concept applies to all GMAT question types and content areas. <\/span>Confidence and accuracy<\/b> are two very important skills to take with you on Test Day, and both are built by practicing regularly. Keep exercising the Data Sufficiency part of your brain and you will see your accuracy rate rise, and with it, your GMAT confidence.<\/span>
\n 
\n

Solving Data Sufficiency Questions<\/h3>
<\/div><\/div><\/div><\/p>\n
\n
\nData Sufficiency (DS) questions are perhaps the most dreaded on the Quantitative Reasoning section of the GMAT. Some people, however, get really good at them\u2014and actually prefer them to Problem Solving questions because often\u00a0you don\u2019t have to solve them<\/b>\u00a0to answer the question. You only need to know whether\u00a0a statement gives enough information to be able to get a solution.
\nFor the rest of GMAT test-takers, Data Sufficiency remains a challenge. Fortunately, these tips will help ease the pain.
\n

Follow linear equation rules for data sufficiency<\/h4>
<\/div><\/div><\/div>
\nThe basic\u00a0\u201cn<\/em>-variables,\u00a0n<\/em>-equations\u201d\u00a0<\/b>rule of linear equations holds that you need\u00a0n<\/em>\u00a0distinct (different) equations to solve for\u00a0n<\/em>\u00a0variables; thus to solve for\u00a0x<\/em>\u00a0and\u00a0y<\/em>, you need two distinct equations that include both x and y. Consider this Data Sufficiency problem:
\nWhat is the value of x?<\/p>\n
    \n
  1. 3x<\/em>\u00a0+ 2y<\/em>\u00a0= 6<\/li>\n
  2. 4y<\/em>\u00a0= 12 \u2013 6x<\/em><\/li>\n<\/ol>\n

    You see that you have two variables and you need to solve for one of them. Boom! Two variables, two equations\u2014select \u201cTogether\u201d and move on, right? Not so fast. This Data Sufficiency problem is\u00a0designed to test whether you are cutting corners<\/b>. If you fail to simplify or rearrange the equation in Statement 2, you will miss seeing that it is THE SAME EQUATION as the one in Statement 1, just multiplied by 2. Thus you only have one equation, even if you combine the statements. So, the correct answer is \u201cNeither.\u201d\u00a0Don\u2019t cut the corner and skip simplification<\/b>.
    \n

    Know when you don\u2019t need to solve for all variables<\/h4>
    <\/div><\/div><\/div>
    \nNot all GMAT linear equation questions require you to solve for two variables. If a Data Sufficiency question asks for the value of an expression, such as 2a<\/em>\u00a0+ 3b<\/em>, you may\u00a0not NEED to solve for both\u00a0a<\/em>\u00a0and\u00a0b<\/em>. You may simply be able\u00a0to solve for what you were asked to find: 2a<\/em>\u00a0+ 3b<\/em>. Here\u2019s an example:
    \nWhat is the value of 7x<\/em>\u00a0+ 3y<\/em>?<\/p>\n
      \n
    1. 56x<\/em>\u00a0+ 24y<\/em>\u00a0= 520<\/li>\n
    2. 8x<\/em>\u00a0+ 5y<\/em>\u00a0= 79 and 40x<\/em>\u00a0+ 25y<\/em>\u00a0= 395<\/li>\n<\/ol>\n

      This question stem does not need to be simplified beyond identifying what we need for sufficiency: the ability to determine the value of the expression in the stem. If you notice that Statement 1 is divisible by 8, and that if you factor out 8 from the left side you are left with 7x<\/em>\u00a0+ 3y<\/em>, you already have enough information to\u00a0answer the question. Statement 1 is indeed sufficient, and you do not need to divide 520 by 8 to confirm.
      \nThe tempting corner to cut comes with Statement 2. Again, two variables, two equations\u2014done, right? You guessed it, these are the same equation presented two different ways. So, the answer is that Statement 1 alone is correct.
      \n

      Remember the rules of taking square roots<\/h4>
      <\/div><\/div><\/div>
      \nData Sufficiency statements often include quadratic equations. When the stem asks for the value of a variable or whether a variable is positive (or negative), you MUST remember the rules of solving quadratics. This includes recalling that there are TWO possible values for\u00a0x<\/em>\u00a0when you know the value of\u00a0x<\/em>\u00b2. Here\u2019s an example:
      \nWhat is the value of x ?<\/p>\n
        \n
      1. x<\/em>\u00a0> 0<\/li>\n
      2. 20 \u2013x<\/em>\u00b2\u00a0= 4<\/li>\n<\/ol>\n

        Right away you see that Statement 1 is insufficient; knowing that\u00a0x<\/em>\u00a0is positive does not give you a single value. Statement 2 requires a bit more work. Rearrange the equation to put\u00a0x<\/em>\u00b2\u00a0on one side:\u00a0x<\/em>\u00b2\u00a0= 16. That means\u00a0x<\/em>\u00a0= 4 and 2 alone is the answer, right? Nope. Whenever you have a value for\u00a0x<\/em>\u00b2, you have\u00a0two possible values<\/b>\u00a0for\u00a0x<\/em>. In this example,\u00a0x<\/em>\u00a0could be 4 but it could also be -4. That means Statement 2 alone is insufficient.
        \nRemembering that same rule, however, means you can now consider the statements together; Statement 1 tells you\u00a0x<\/em>\u00a0is positive, so taken together you know\u00a0x<\/em>\u00a0= 4. Done.
        \n(Bonus info: On the GMAT the radical symbol always gives you only the positive square root. So, although\u00a0x<\/em>\u00b2\u00a0= 9 means\u00a0x<\/em>\u00a0= 3 or\u00a0x<\/em>\u00a0= -3, remember that \u221a9\u00a0=3.\u00a0Always.)
        \nThese are but a few tips for avoiding common pitfalls on the GMAT. I will discuss others in a later post. Next week, we switch gears to the Verbal section, so buckle up.
        \n

        <\/span><\/span><\/div>
        \n
        \n
        <\/div>

        Jennifer Mathews Land has taught for Kaplan since 2009. She prepares students to take the GMAT, GRE, ACT, and SAT and was named Kaplan\u2019s Alabama-Mississippi Teacher of the Year in 2010. Prior to joining Kaplan, she worked as a grad assistant in a university archives, a copy editor for medical web sites, and a dancing dinosaur at children’s parties. Jennifer holds a PhD and a master\u2019s in library and information studies (MLIS) from the University of Alabama, and an AB in English from Wellesley College. When she isn\u2019t teaching, she enjoys watching Alabama football and herding cats.<\/p>\n<\/div><\/div>

        <\/div><\/div>
        Jennifer Land<\/strong><\/div><\/div><\/div><\/div>\n<\/section><\/div><\/p>\n

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        <\/span><\/p>\n<\/div>\n\t\t<\/div><\/div><\/p>\n<\/div>\n<\/div>\n","protected":false},"excerpt":{"rendered":"

        Data Sufficiency must be practiced every day. It\u2019s like these questions use a part of your brain that is seldom employed for other purposes; much like a little-used muscle, you need to warm up and use it regularly or it won\u2019t work well when needed. The Critical Thinking skills tapped by Data Sufficiency require regular […]<\/p>\n","protected":false},"author":1,"featured_media":27613,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":[],"categories":[55],"tags":[56],"_links":{"self":[{"href":"https:\/\/wpapp.kaptest.com\/study\/wp-json\/wp\/v2\/posts\/7242"}],"collection":[{"href":"https:\/\/wpapp.kaptest.com\/study\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/wpapp.kaptest.com\/study\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/wpapp.kaptest.com\/study\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/wpapp.kaptest.com\/study\/wp-json\/wp\/v2\/comments?post=7242"}],"version-history":[{"count":2,"href":"https:\/\/wpapp.kaptest.com\/study\/wp-json\/wp\/v2\/posts\/7242\/revisions"}],"predecessor-version":[{"id":34525,"href":"https:\/\/wpapp.kaptest.com\/study\/wp-json\/wp\/v2\/posts\/7242\/revisions\/34525"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/wpapp.kaptest.com\/study\/wp-json\/wp\/v2\/media\/27613"}],"wp:attachment":[{"href":"https:\/\/wpapp.kaptest.com\/study\/wp-json\/wp\/v2\/media?parent=7242"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/wpapp.kaptest.com\/study\/wp-json\/wp\/v2\/categories?post=7242"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/wpapp.kaptest.com\/study\/wp-json\/wp\/v2\/tags?post=7242"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}