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Did you know that you can attend the first session of any of our online or in-person GMAT courses absolutely free? We\u2019re not kidding! Check out our upcoming courses here<\/a>.<\/em><\/strong><\/p>\n How are the GMAT test writers going to hide information in plain sight and get you to fall into traps?<\/p>\n Try out this problem in our <\/span>Know the Code<\/span><\/a> series and then we\u2019ll dig in to figure out what\u2019s going on. Note: this one\u2019s from the GMATPrep\u00ae<\/b><\/span>\u00a0free practice problems.<\/span><\/p>\n \u201c*A certain group of car dealerships agreed to donate <\/span>x<\/span><\/i> dollars to a Red Cross chapter for each car sold during a 30-day period. What was the total amount that was expected to be donated?<\/span><\/p>\n \u201c(1) A total of 500 cars were expected to be sold.<\/span><\/p>\n \u201c(2) 60 more cars were sold than expected, so that the total amount actually donated was $28,000.\u201d<\/span><\/p>\n (If you are new to Data Sufficiency, <\/span>start here<\/span><\/a> and come back to this article later.)<\/span><\/p>\n Ready?<\/span><\/p>\n 1-second Glance.<\/strong> DS. Wall of words! Story\u2014will need to translate.<\/span><\/p>\n Read<\/strong>.<\/strong> Put yourself in the story. You\u2019re coordinating all of these donations. This group agreed to donate <\/span>x<\/span><\/i> dollars <\/span>per car sold<\/span><\/i> during a certain period.<\/span><\/p>\n Then, there\u2019s some curiously-worded language: they\u2019re asking for the amount expected to be donated. That\u2019s weird\u2014what would a problem normally ask for?<\/span><\/p>\n Most problems would ask for the amount that was actually donated. So, presumably, the amount actually donated does not match the amount expected to be donated. We\u2019ll need to keep these two different amounts straight, so factor this into your notes.<\/span><\/p>\n Jot.<\/strong><\/p>\n $<\/span>x<\/span><\/i> \/ car<\/span><\/p>\n C<\/span><\/i> = # of cars <\/span>expected<\/span><\/p>\n Total expected donation = <\/span>xC<\/span><\/i><\/p>\n Reflect<\/strong>.<\/strong> Briefly: what could change in this scenario to create a difference between total <\/span>actually<\/span><\/i> donated and total <\/span>expected<\/span><\/i> to be donated?<\/span><\/p>\n The amount, $<\/span>x<\/span><\/i>, donated per car sold could change; maybe the dealerships change their pledge?<\/span><\/p>\n It could also be the case that they expect to sell a certain number of cars in the given period, but they might end up selling a different number.<\/span><\/p>\n Let\u2019s look at the first statement.<\/span><\/p>\n \u201c(1) A total of 500 cars were expected to be sold.\u201d<\/span><\/p>\n This is half of the equation but indicates nothing about the dollar amount donated per car. Without any information about the money, it\u2019s impossible to figure out the total amount that was expected to be donated. <\/span><\/p>\n Statement (1) is insufficient; eliminate choices (A) and (D).<\/span><\/p>\n \u201c(2) 60 more cars were sold than expected, so that the total amount actually donated was $28,000.\u201d<\/span><\/p>\n Here\u2019s where it gets interesting. The information here is more convoluted\u2014be careful.<\/span><\/p>\n If <\/span>C<\/span><\/i> is the # of cars expected to be sold, then the actual number of cars sold is <\/span>C<\/span><\/i> + 60. If the per-car donation is still $<\/span>x<\/span><\/i>, then we can write a new formula for the amount actually donated\u2014and this figure is provided in the statement, too!<\/span><\/p>\n Total amount actually donated = ($x \/ car)(number of cars actually sold)<\/span><\/p>\n 28,000 = <\/span>x<\/span><\/i>(<\/span>C<\/span><\/i> + 60)<\/span><\/p>\n This information is for the actual amount donated, not the expected amount\u2014and the problem asks for the expected amount. Can you do anything with this to figure out <\/span>x<\/span><\/i> and <\/span>C<\/span><\/i>?<\/span><\/p>\n There is another formula, but that one has three variables: <\/span>T<\/span><\/i> = <\/span>xC<\/span><\/i>, where the <\/span>T<\/span><\/i> is the total expected donation. There isn\u2019t a way to manipulate the two equations to solve for a single numerical value for <\/span>T<\/span><\/i>.<\/span><\/p>\n Statement (2) is not sufficient; cross off answer (B).<\/span><\/p>\n Finally, put the two statements together. Now, you have <\/span>C<\/span><\/i> = 50 and 28,000 = <\/span>x<\/span><\/i>(<\/span>C<\/span><\/i> + 60). Plug in and you can solve for <\/span>x<\/span><\/i>. (Don’t actually solve\u2014this is DS!)<\/span><\/p>\n If you have <\/span>x<\/span><\/i>, can you do anything else? Yes! Statement (1) still tells you <\/span>C<\/span><\/i>! Multiply those two together to get the desired value: <\/span>T<\/span><\/i> = <\/span>xC<\/span><\/i>.<\/span><\/p>\n The correct answer is (C).<\/span><\/p>\n When you go through this solution, the question seems pretty straightforward. But it would be easy, during the stress of the test, to fall into a couple of different traps.<\/span><\/p>\n First, if your notes aren\u2019t totally clear about the \u201cexpected\u201d stuff vs. the \u201cactual\u201d stuff, it would be easy to conclude that statement (2) is sufficient on its own, leading you to incorrect answer (B). That\u2019s where the <\/span>Reflect<\/strong> stage is so important\u2014if you can establish ahead of time that these two scenarios exist, you\u2019ll be more likely to keep the information straight when you get to statement (2).<\/span><\/p>\n Second, once you do put the two statements together, you have to do a sort of double-loop: first, you use the two statements to realize that you can solve for <\/span>x<\/span><\/i>, and then you have to remember that one of those two pieces of information actually did give you <\/span>C <\/span><\/i>in the first place. The trap: you already used the given information from the two statements and, since there isn\u2019t anything new elsewhere to use, you think that that\u2019s it\u2014you can find <\/span>x<\/span><\/i>, but that\u2019s not enough by itself.<\/span><\/p>\n How to avoid that trap? Two things. First, write out your work fully and carefully. Second, know what you need to find <\/span>before<\/span><\/i> you start to solve.<\/span><\/p>\n If you have <\/span>C<\/span><\/i> = 50 written right there, clearly, on your scrap paper and you\u2019ve just said to yourself, \u201cThe two together will be sufficient if I can find both <\/span>C<\/span><\/i> and <\/span>x<\/span><\/i>,\u201d then you can say to yourself right up front, \u201cOh, I already have <\/span>C<\/span><\/i>! Great, all I need to do is find <\/span>x<\/span><\/i>.\u201d When the two statements together give you <\/span>x<\/span><\/i>, voila: you\u2019re done.<\/span><\/p>\n (1) For story problems, put yourself in the story. Pay attention to unusual language cues and take the time to <\/span>Reflect<\/strong> on what they mean. That 15 or 30 seconds is well spent if you avoid traps or careless mistakes later on!<\/span><\/p>\n (2) Write everything down carefully. Before you evaluate a piece of information, remind yourself what you would need to find in order to say that the info is sufficient.<\/span><\/p>\n (3) Turn any knowledge you gain into Know the Code flash cards:<\/span><\/p>\n * GMATPrep<\/span>\u00ae<\/span> questions courtesy of the Graduate Management Admissions Council. Usage of this question does not imply endorsement by GMAC.\u00a0?<\/span><\/p>\n Can\u2019t get enough of Stacey\u2019s GMAT mastery? Attend the first session of one of her upcoming GMAT courses<\/a> absolutely free, no strings attached. Seriously.\u00a0<\/strong><\/em><\/p>\n Did you know that you can attend the first session of any of our online or in-person GMAT courses absolutely free? We\u2019re not kidding! Check out our upcoming courses here. How are the GMAT test writers going to hide information in plain sight and get you to fall into traps?<\/p>\n","protected":false},"author":6,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[15,873,929,52871,930,2,8],"tags":[150,52953,53019,698],"yst_prominent_words":[],"class_list":["post-12839","post","type-post","status-publish","format-standard","hentry","category-data-suff","category-for-current-studiers","category-gmat-prep","category-gmat-strategies","category-gmat-study-guide","category-how-to-study","category-quant-on-gmat","tag-data-sufficiency","tag-gmat-code","tag-know-the-gmat-code","tag-story-problems"],"_links":{"self":[{"href":"https:\/\/www.manhattanprep.com\/gmat\/wp-json\/wp\/v2\/posts\/12839","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.manhattanprep.com\/gmat\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.manhattanprep.com\/gmat\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.manhattanprep.com\/gmat\/wp-json\/wp\/v2\/users\/6"}],"replies":[{"embeddable":true,"href":"https:\/\/www.manhattanprep.com\/gmat\/wp-json\/wp\/v2\/comments?post=12839"}],"version-history":[{"count":6,"href":"https:\/\/www.manhattanprep.com\/gmat\/wp-json\/wp\/v2\/posts\/12839\/revisions"}],"predecessor-version":[{"id":13791,"href":"https:\/\/www.manhattanprep.com\/gmat\/wp-json\/wp\/v2\/posts\/12839\/revisions\/13791"}],"wp:attachment":[{"href":"https:\/\/www.manhattanprep.com\/gmat\/wp-json\/wp\/v2\/media?parent=12839"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.manhattanprep.com\/gmat\/wp-json\/wp\/v2\/categories?post=12839"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.manhattanprep.com\/gmat\/wp-json\/wp\/v2\/tags?post=12839"},{"taxonomy":"yst_prominent_words","embeddable":true,"href":"https:\/\/www.manhattanprep.com\/gmat\/wp-json\/wp\/v2\/yst_prominent_words?post=12839"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}
\n![\"Manhattan](\"\/\/www.manhattanprep.com\/gmat\/wp-content\/uploads\/sites\/18\/2017\/01\/quant-process-1.png\")
<\/p>\nKey Takeaways for Knowing the Code<\/strong><\/h4>\n
![\"Manhattan](\"\/\/www.manhattanprep.com\/gmat\/wp-content\/uploads\/sites\/18\/2017\/01\/sk-402-know-the-code-flash-cards.png\")
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\n![\"stacey-koprince\"](\"https:\/\/cdn2.manhattanprep.com\/gmat\/wp-content\/uploads\/sites\/18\/2015\/06\/stacey-koprince-150x150.png\")
<\/a>Stacey Koprince<\/a> is a Manhattan Prep instructor based in Montreal, Canada and Los Angeles, California.<\/strong> Stacey has been teaching the GMAT, GRE, and LSAT \u00a0for more than 15 years and is one of the most well-known instructors in the industry. Stacey loves to teach and is absolutely fascinated by standardized tests. Check out Stacey\u2019s upcoming GMAT courses here<\/a>.<\/em><\/p>\n","protected":false},"excerpt":{"rendered":"