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You can attend the first session of any of our online or in-person GRE courses absolutely free. Crazy, right? <\/i><\/b>Check out our upcoming courses here<\/i><\/b><\/a>.<\/i><\/b><\/p>\n <\/i><\/b>In <\/span>my last blog post<\/span><\/a>, we practiced using variables to solve Quant word problems\u2014and we solved some problems <\/span>without<\/span><\/i> using variables, too. The big takeaway: you don\u2019t have to start every word problem with a tidy little list of variables and equations! It\u2019s okay to focus on the <\/span>numbers<\/span><\/i> in the problem first. However, variables are sometimes the key ingredient to getting a GRE problem right. In this article, we\u2019ll try using variables to solve some tougher GRE Quant word problems. <\/span><\/p>\n Here\u2019s one of my favorite problems from the <\/span>5lb. Book of GRE Practice Problems<\/span><\/a>. Give it a try before you keep reading:<\/span><\/p>\n The yoga company Yoga for Life offers 45-minute classes at $12 per class. If the number of minutes Randolf spent doing yoga this month was 132 greater than the number of dollars he paid, how many classes did he attend? <\/span><\/em><\/p>\n Let\u2019s treat this like a Numeric Entry problem, meaning that you don\u2019t have any <\/span>answer choices to help you out<\/span><\/a>. (If you did, Backsolving would probably be the way to go!) There also isn\u2019t an obvious way forward that only uses numbers. This is where a lot of people get stuck. You might start with the first sentence, and write down something like \u201c45m = 12\u201d, or \u201c45 = 12c\u201d. But are those actually the right equations? Unfortunately, no. In order to solve this one, you need to be extremely clear about <\/span>what your variables represent<\/b>. <\/span><\/p>\n Let\u2019s say that <\/span>m<\/span><\/i> represents the number of minutes Randolf spent doing yoga this month, and <\/span>c<\/span><\/i> represents the number of classes he took. That\u2019s actually the first thing I\u2019d jot down on my scratch paper.<\/span><\/p>\n Now<\/span><\/i> we can start creating equations. Or can we? Our first guess, 45m = 12, would be read like this:<\/span><\/p>\n \u201c45 times the number of minutes equals 12.\u201d<\/span><\/p>\n That doesn\u2019t make sense\u2014and by the way, reading your equations back to yourself in plain English is a good way to make sure they make logical sense. The number 12 doesn\u2019t have anything to do with the number of minutes. It\u2019s a number of <\/span>dollars<\/span><\/i>. Scanning the rest of the problem, the total number of dollars is going to be important. We\u2019ll need a variable for that, as well.<\/span><\/p>\n Okay, back to that first sentence. You might be tempted to write something like \u201c45m = 12d\u201d at this point. Read it back to yourself first! There\u2019s no reason to multiply the number of minutes by 45, or to multiply the number of dollars by 12. Here\u2019s where you actually need to go next:<\/p>\n If you know how long one class is, you can relate the number of classes to the total amount of time.<\/b><\/p>\n The same is true for the <\/span>cost<\/span><\/i> of each class. If you know how much one class costs, you can relate the total number of classes to the total amount of money spent. In other words:<\/span><\/p>\n You can express both <\/span>m<\/span><\/i> and <\/span>d<\/span><\/i> in terms of <\/span>c<\/span><\/i>! The total number of minutes is 45 times the total number of classes. The number of dollars is 12 times the number of classes.<\/span><\/p>\n Finally, use this information to write a second equation and wrap up the problem.<\/span><\/p>\n Solving that equation tells you that Randolf took four yoga classes this month.<\/p>\n Okay, let\u2019s focus in. Sometimes, in GRE word problems, the text tells you about a <\/span>cost per unit<\/span><\/i>, or <\/span>time per unit<\/span><\/i>, or something similar. In this problem, we learned about the <\/span>cost per class<\/span><\/i> and the <\/span>time per class<\/span><\/i>. A problem could also tell you about <\/span>miles per hour, dollars per gallon, <\/span><\/i>or even\u2014as in the following problem\u2014<\/span>calories per doughnut. <\/span><\/i><\/p>\n Krunchy Kustard sells only two kinds of doughnuts: glazed and cream-filled. A glazed doughnut has 200 calories, and a cream-filled doughnut has 360 calories. If Felipe ate 5 doughnuts totaling 1,640 calories, how many were glazed?<\/span><\/em><\/p>\n (A) 1 This problem gives you two pieces of information: the total number of doughnuts and the total number of calories. It also tells you the number of <\/span>calories per doughnut<\/span><\/i>, which is what will let you relate the two pieces of info and create good equations. Try it out before looking at my scratch work:<\/span><\/p>\n Got it? Okay, let\u2019s try one last problem that gives you information in a similar way. This one is trickier!<\/p>\n When traveling on the highway, a certain car averages 60 miles per hour and uses 2 gallons of gasoline per hour. When traveling in the city, the same car averages 30 miles per hour and uses 1.5 gallons of gasoline per hour. If the car uses a total of 8 gallons of gasoline over the course of a 210-mile trip, how many hours of the trip were spent traveling on the highway? <\/span><\/em><\/p>\n Try it on your own first. If you get stuck, look back at the two previous problems. This one is very similar. Your variables should be <\/span>c<\/span><\/i>, \u201ccity hours,\u201d and <\/span>h<\/span><\/i>, \u201chighway hours.\u201d<\/span><\/p>\n Ready? Here\u2019s how to approach it:<\/span><\/p>\n Finish up by solving those two equations\u2014you\u2019ll find that the car spent 2.5 hours on the highway. <\/span><\/p>\n Look out for word problems like these ones in the future, and don\u2019t let the GRE confuse you! If a problem tells you about the number of calories in one doughnut, you can convert that to the total number of calories. If a problem tells you how many miles a car travels per hour, you can convert that to find the total number of miles traveled. These problems might be intimidating, but you can solve them the same way every time\u2014be consistent, and you\u2019ll be well on your way to mastering GRE Quant. ?<\/span><\/p>\n See that \u201cSUBSCRIBE\u201d button in the top right corner? Click on it to receive all our GRE blog updates straight to your inbox!<\/i><\/b><\/p>\n Chelsey Cooley<\/a> You can attend the first session of any of our online or in-person GRE courses absolutely free. Crazy, right? Check out our upcoming courses here. In my last blog post, we practiced using variables to solve Quant word problems\u2014and we solved some problems without using variables, too. The big takeaway: you don\u2019t have to start […]<\/p>\n","protected":false},"author":127,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[15,2,474284,921840,421,6,7,9,733445],"tags":[1362405],"yst_prominent_words":[],"class_list":["post-10321","post","type-post","status-publish","format-standard","hentry","category-gre-math-algebra","category-challenge-problems","category-current-studiers","category-gre-prep-2","category-gre-quant-2","category-gre-strategies","category-how-to-study","category-math-gre-strategies","category-study-tips-2","tag-gre-variables"],"_links":{"self":[{"href":"https:\/\/www.manhattanprep.com\/gre\/wp-json\/wp\/v2\/posts\/10321","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.manhattanprep.com\/gre\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.manhattanprep.com\/gre\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.manhattanprep.com\/gre\/wp-json\/wp\/v2\/users\/127"}],"replies":[{"embeddable":true,"href":"https:\/\/www.manhattanprep.com\/gre\/wp-json\/wp\/v2\/comments?post=10321"}],"version-history":[{"count":5,"href":"https:\/\/www.manhattanprep.com\/gre\/wp-json\/wp\/v2\/posts\/10321\/revisions"}],"predecessor-version":[{"id":10416,"href":"https:\/\/www.manhattanprep.com\/gre\/wp-json\/wp\/v2\/posts\/10321\/revisions\/10416"}],"wp:attachment":[{"href":"https:\/\/www.manhattanprep.com\/gre\/wp-json\/wp\/v2\/media?parent=10321"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.manhattanprep.com\/gre\/wp-json\/wp\/v2\/categories?post=10321"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.manhattanprep.com\/gre\/wp-json\/wp\/v2\/tags?post=10321"},{"taxonomy":"yst_prominent_words","embeddable":true,"href":"https:\/\/www.manhattanprep.com\/gre\/wp-json\/wp\/v2\/yst_prominent_words?post=10321"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}
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\n![\"Chelsey](\"https:\/\/cdn2.manhattanprep.com\/gre\/wp-content\/uploads\/sites\/19\/2015\/11\/chelsey-cooley-150x150.jpg\" "\\"Chelsey")
<\/a> is a Manhattan Prep instructor based in Seattle, Washington.<\/strong>\u00a0<\/em><\/i><\/b>Chelsey always followed her heart when it came to her education. Luckily, her heart led her straight to the perfect background for GMAT and GRE teaching: she has undergraduate degrees in mathematics and history, a master\u2019s degree in linguistics, a 790 on the GMAT, and a perfect 170Q\/170V on the GRE.\u00a0<\/em><\/i>Check out Chelsey\u2019s upcoming GRE prep offerings here<\/a>.<\/em><\/i><\/p>\n","protected":false},"excerpt":{"rendered":"