Many GMAT-takers underestimate the valuable information given there.\u00a0 Diagrams on GMAT Problem Solving are basically drawn to scale.\u00a0 The only time that doesn't hold is if you see the note printed \"Diagram not necessarily to scale\" --- then, all bets are off about how the figure actually looks.\u00a0 But if that disclaimer is not printed, what you have on GMAT Problem-Solving is a diagram drawn to scale, guaranteed.<\/p>\n
<\/p>\n
What You Can Assume<\/h2>\n
Consider the following question:<\/p>\n
<\/p>\n
1) The area of rectangle ABCD is closest to which of the following?<\/p>\n
(A) 100<\/p>\n (B) 130<\/p>\n (C) 170<\/p>\n (D) 200<\/p>\n (E) 230<\/p>\n <\/p>\n Suppose we don't know the math to answer this question. \u00a0We are told it's a rectangle, so we know the angles must be right angles, and we know the area must be length (AD) times height (AB).\u00a0 We know the height is 10.\u00a0 We know AD is drawn to scale.\u00a0 It definitely is longer than AB, so the area is definitely larger than 10 x 10 (answer (A) is out).\u00a0 AD doesn't look as long as twice AB, so the area is definitely less than 10 x 20 (answers (D) & (E) are out).\u00a0 Notice, with pure spatial estimation, we eliminated three of the five answer choices, so it will be to our advantage to guess randomly from the remaining two if we can't decide between them.\u00a0 Estimating from size can be a huge help if you don't remember the way to solve the problem.<\/p>\n BTW, the real math solution to that question:\u00a0 from the properties of the 30-60-90 triangle (ACD), we know that AD = 10*sqrt(3), and since sqrt(3) is approximately 1.7, AD is approximately 17, and the area is approximately 170. Answer =\u00a0C<\/strong>.<\/p>\n <\/p>\n <\/p>\n Here's another.\u00a0 This is from the GMAT OG.\u00a0 In the GMAT OG12e, it's Problem Solving #210, and in the OG13e, it's Problem Solving #211.<\/p>\n <\/p>\n \u00a0 2) In the coordinate system above, which of the following is the equation of line l?<\/p>\n (A) 2x \u2013 3y = 6<\/p>\n (B) 2x + 3y = 6<\/p>\n (C) 3x + 2y = 6<\/p>\n (D) 2x \u2013 3y = \u20136<\/p>\n (E) 3x \u2013 2y =\u20136<\/p>\n <\/p>\n A student asked about this question: how do we know that the x-intercept of line l is 3 and the y-intercept is 2?\u00a0 Well, technically, we don't know that they are exactly 3 and 2, but we know from the diagram that if they are not exactly 3 and 2, they are very very close.\u00a0 Thus, x-intercept = 3 and y-intercept= 2 make an excellent starting point: even if they are not spot-on correct, they are very good approximations.\u00a0 As it happens, the exact values themselves lead to the correct answer of\u00a0B<\/strong>.<\/p>\n <\/p>\n <\/p>\n You can't assume lines are parallel, because many special properties are true only if two lines are exactly parallel, but the naked eye cannot distinguish exactly parallel from almost parallel.\u00a0 For example:<\/p>\n <\/p>\n These lines look parallel, right?\u00a0 They're not: they are 1\/10 of one degree off from exactly parallel, and that means: none of the special geometry facts for parallel lines would apply to these lines.<\/p>\n The same applies to right angles.\u00a0 An angle of 89.9\u00ba or 90.1\u00ba will look like a right angle to the unaided eye, but if it's not an exact right angle, none of the special right angle facts (like the Pythagorean Theorem) will apply.\u00a0 For example:<\/p>\n These are two squares, right?\u00a0 Think again.\u00a0 Here is each one with individual measurements:<\/p>\n ABCD is actually a rhombus: four equal sides, and opposite pairs of angles equal, but not equiangular, the way a square should be.<\/p>\n EFGH is actually an isosceles trapezoid: equal pairs of base angles, and the legs (EF & GH) are congruent.\u00a0 Both look like squares, but neither one is.<\/p>\n None of the parallel properties in geometry are true for \"almost parallel,\" and none of the right angle properties are true for \"almost a right angle.\"<\/p>\n <\/p>\n Diagrams on GMAT Problem Solving are drawn to scale.\u00a0 That serves you very well when you are approximating.\u00a0 That doesn't help you, and may mislead you, if you need something to be exactly true.<\/p>\n Here's a practice PS question with a diagram drawn to scale:<\/p>\n https:\/\/gmat.magoosh.com\/questions\/106<\/a><\/p>\n This post was written by Mike McGarry, GMAT expert at\u00a0Magoosh<\/a>, and originally posted\u00a0here<\/a>.<\/p>\n","protected":false},"excerpt":{"rendered":" Using the information given in diagrams to your advantage The following sentences appear in the directions to the GMAT Problem Solving questions. A figure accompanying a problem solving questions…<\/p>\n","protected":false},"author":133,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[9,783,243,717,736],"tags":[],"class_list":["post-11350","post","type-post","status-publish","format-standard","hentry","category-gmat","category-magoosh-blog","category-blog","category-problem-solving-gmat","category-quant-gmat","entry"],"aioseo_notices":[],"_links":{"self":[{"href":"https:\/\/gmatclub.com\/blog\/wp-json\/wp\/v2\/posts\/11350","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\/133"}],"replies":[{"embeddable":true,"href":"https:\/\/gmatclub.com\/blog\/wp-json\/wp\/v2\/comments?post=11350"}],"version-history":[{"count":3,"href":"https:\/\/gmatclub.com\/blog\/wp-json\/wp\/v2\/posts\/11350\/revisions"}],"predecessor-version":[{"id":11354,"href":"https:\/\/gmatclub.com\/blog\/wp-json\/wp\/v2\/posts\/11350\/revisions\/11354"}],"wp:attachment":[{"href":"https:\/\/gmatclub.com\/blog\/wp-json\/wp\/v2\/media?parent=11350"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/gmatclub.com\/blog\/wp-json\/wp\/v2\/categories?post=11350"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/gmatclub.com\/blog\/wp-json\/wp\/v2\/tags?post=11350"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}![\"\"](\"https:\/\/magoosh.com\/gmat\/files\/2012\/05\/drawn-1.png\")
<\/a><\/p>\n<\/a><\/p>\nWhat You Can't Assume<\/h2>\n
<\/a><\/p>\n<\/a><\/p>\n<\/a><\/p>\n<\/a><\/p>\nThe Moral<\/h2>\n