{"id":26616,"date":"2014-12-08T03:00:32","date_gmt":"2014-12-08T10:00:32","guid":{"rendered":"https:\/\/gmatclub.com\/blog\/2014\/12\/picking-numbers-on-gmat-data-sufficiency-permissible-vs-sufficient\/"},"modified":"2014-12-08T03:00:32","modified_gmt":"2014-12-08T10:00:32","slug":"picking-numbers-on-gmat-data-sufficiency-permissible-vs-sufficient","status":"publish","type":"post","link":"https:\/\/gmatclub.com\/blog\/picking-numbers-on-gmat-data-sufficiency-permissible-vs-sufficient\/","title":{"rendered":"Picking Numbers on GMAT Data Sufficiency: Permissible vs. Sufficient"},"content":{"rendered":"
\"GMAT<\/a><\/p>\n

Pick numbers carefully and strategically on GMAT Data Sufficiency Yes\/No questions.<\/p>\n<\/div>\n

One of the hallmark points of confusion on GMAT Data Sufficiency<\/a> is the dreaded Yes\/No question.<\/p>\n

In a Value question<\/a>, such as \u201cWhat is the value of x?\u201d the question of sufficiency is a familiar one: if you can solve for x, you have sufficiency.\u00a0 But in a Yes\/No question, especially when variables are involved, finding a solid answer can be a much cloudier process.<\/p>\n

Sample GMAT Data Sufficiency Yes\/No Question<\/h4>\n

The best way to clear this fog is with a concrete example.\u00a0 Let\u2019s look at this Data Sufficiency question, along with its first statement:<\/p>\n

Is x positive?<\/strong><\/p>\n

(1) x^2 > 1<\/strong><\/p>\n

Is Statement (1) sufficient to answer the question?\u00a0 Unless you have a comprehensive understanding of the underlying Number Properties<\/a> at work here, your first reaction to this statement is likely to try out different numerical values for x, because working with real numbers instead of variables<\/a> will be a much more comfortable place for most of us. \u00a0You are free to try out any value for x, but your first consideration in checking this statement should be that the number you pick is\u00a0permissible<\/em>, according to the statement.\u00a0 If it is not, don’t consider the number as an example.<\/p>\n

Picking a Permissible Number<\/h4>\n

Is zero a permissible number to use here?<\/strong>\u00a0 Well, if x = 0, then x^2 is also 0, and this statement tells you that x^2 has to be greater than 1.\u00a0 You must take the statements as true, so zero is NOT a number you can use here (not permissible).<\/p>\n

How about x = 2?<\/strong>\u00a0 That is in permissible territory, because 2^2 = 4, and 4 > 1.\u00a0 But even that is only half the battle.\u00a0 Now that you know x = 2 is a permissible example, you have to see what answer it yields to the original question, \u201cIs x positive?\u201d\u00a0Since 2 is a positive number, the answer here is \u201cYes.\u201d<\/p>\n

Sufficiency on Yes\/No Data Sufficiency Questions<\/h4>\n

Now there’s one example in the bank, and you know that, given the information in this statement, the answer to the question can be \u201cYes.\u201d\u00a0 But is that enough to declare sufficiency?\u00a0 Unfortunately, it is not.<\/strong>\u00a0 If this statement is sufficient to answer the question, it will give you a consistent<\/em> Yes or No answer. You know now that the answer could be Yes, but could it also be No?<\/p>\n

Well, if the answer could be No, then that would mean x could be negative or zero. \u00a0You\u2019ve already seen that x can\u2019t be zero (because it\u2019s not permissible, remember?), so what about x being negative?<\/strong>\u00a0 Let\u2019s take the flip side of the other example and try x = -2.\u00a0 It would certainly answer the question stem with a No, but is it permissible?<\/p>\n

Remember, the statement mandates that x > 1.\u00a0 Working a little calculation, (-2)^2 equals (-2)(-2), and since the product of two negative numbers is a positive number, x^2 = 4 when x = -2.\u00a0 So this second example is permissible after all, and it answers the question \u201cIs x positive?\u201d with a resounding \u201cNo.\u201d Since you have answered the question with a potential \u201cYes\u201d (when x = 2) and a potential \u201cNo\u201d (when x = -2), this statement is actually\u00a0<\/strong>insufficient<\/strong>\u00a0<\/em>in the end; further information is required to determine whether or not x is positive.<\/p>\n

The Takeaway<\/h4>\n

As you see, it is absolutely necessary to remember what must be assumed as true (the statements) and what may or may not be true (the question stem) when Picking Numbers in these types of problems.<\/p>\n

While this specific example is not as challenging as some, and you may have logically thought through it with number properties rules from the outset, this thought process is vital to learn for these types of questions, and will be most helpful with the most challenging questions<\/a>, where you cannot gather the potential scenarios quickly at a glance without doing some scratch work<\/a>. When the Yes\/No monster rears its ugly, convoluted head, never forget when picking numbers: First permissible, then Sufficient!<\/strong><\/p>\n

Test your GMAT skills. Sign\u00a0up for a\u00a0free GMAT practice test<\/a>.<\/em><\/p>\n

The post Picking Numbers on GMAT Data Sufficiency: Permissible vs. Sufficient<\/a> appeared first on Kaplan GMAT Blog<\/a>.<\/p>\n","protected":false},"excerpt":{"rendered":"

Pick numbers carefully and strategically on GMAT Data Sufficiency Yes\/No questions. One of the hallmark points of confusion on GMAT Data Sufficiency is the dreaded Yes\/No question. In a Value…<\/p>\n","protected":false},"author":120,"featured_media":0,"comment_status":"closed","ping_status":"1","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[9,558,243,940],"tags":[],"class_list":["post-26616","post","type-post","status-publish","format-standard","hentry","category-gmat","category-kaplan-blog","category-blog","category-gmat-prep-gmat","entry"],"aioseo_notices":[],"_links":{"self":[{"href":"https:\/\/gmatclub.com\/blog\/wp-json\/wp\/v2\/posts\/26616","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\/120"}],"replies":[{"embeddable":true,"href":"https:\/\/gmatclub.com\/blog\/wp-json\/wp\/v2\/comments?post=26616"}],"version-history":[{"count":0,"href":"https:\/\/gmatclub.com\/blog\/wp-json\/wp\/v2\/posts\/26616\/revisions"}],"wp:attachment":[{"href":"https:\/\/gmatclub.com\/blog\/wp-json\/wp\/v2\/media?parent=26616"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/gmatclub.com\/blog\/wp-json\/wp\/v2\/categories?post=26616"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/gmatclub.com\/blog\/wp-json\/wp\/v2\/tags?post=26616"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}