<?xml version="1.0" encoding="UTF-8"?><rss version="2.0" xmlns:content="http://purl.org/rss/1.0/modules/content/" xmlns:wfw="http://wellformedweb.org/CommentAPI/" xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:atom="http://www.w3.org/2005/Atom" xmlns:sy="http://purl.org/rss/1.0/modules/syndication/" xmlns:slash="http://purl.org/rss/1.0/modules/slash/" > <channel> <title>GMAT Ratios – GMAT</title> <atom:link href="https://www.manhattanprep.com/gmat/blog/tag/gmat-ratios/feed/" rel="self" type="application/rss+xml" /> <link>https://www.manhattanprep.com/gmat</link> <description>GMAT Prep Course, Best GMAT Class & Study Books | Manhattan Prep GMAT</description> <lastBuildDate>Thu, 05 Sep 2019 15:54:10 +0000</lastBuildDate> <language>en-US</language> <sy:updatePeriod> hourly </sy:updatePeriod> <sy:updateFrequency> 1 </sy:updateFrequency> <generator>https://wordpress.org/?v=6.3.2</generator> <item> <title>The Knowledge Trove that Is a GMAT Ratio</title> <link>https://www.manhattanprep.com/gmat/blog/the-knowledge-trove-that-is-a-gmat-ratio/</link> <dc:creator><![CDATA[Reed Arnold]]></dc:creator> <pubDate>Thu, 09 Feb 2017 19:34:40 +0000</pubDate> <category><![CDATA[For Current Studiers]]></category> <category><![CDATA[Fractions, Decimals, Percents]]></category> <category><![CDATA[GMAT Prep]]></category> <category><![CDATA[GMAT Strategies]]></category> <category><![CDATA[GMAT Study Guide]]></category> <category><![CDATA[Quant]]></category> <category><![CDATA[GMAT Ratios]]></category> <guid isPermaLink="false">http://www.manhattanprep.com/gmat/?p=12932</guid> <description><![CDATA[<p>Did you know that you can attend the first session of any of our online or in-person GMAT courses absolutely free? We’re not kidding! Check out our upcoming courses here. ‘Ratios?’ You might be thinking. ‘Those are easy. Pretty sure I get those.’ Wait. Let’s pretend I am the eccentric owner of a pet store, […]</p> <p>The post <a rel="nofollow" href="https://www.manhattanprep.com/gmat/blog/the-knowledge-trove-that-is-a-gmat-ratio/">The Knowledge Trove that Is a GMAT Ratio</a> appeared first on <a rel="nofollow" href="https://www.manhattanprep.com/gmat">GMAT</a>.</p> ]]></description> <content:encoded><![CDATA[<p><img decoding="async" fetchpriority="high" class="alignnone size-full wp-image-13174" src="https://cdn2.manhattanprep.com/gmat/wp-content/uploads/sites/18/2017/02/2-9-17-blog-1.png" alt="Manhattan Prep GMAT Blog - The Knowledge Trove that Is a GMAT Ratio by Reed Arnold" width="676" height="264" srcset="https://cdn2.manhattanprep.com/gmat/wp-content/uploads/sites/18/2017/02/2-9-17-blog-1.png 676w, https://cdn2.manhattanprep.com/gmat/wp-content/uploads/sites/18/2017/02/2-9-17-blog-1-300x117.png 300w" sizes="(max-width: 676px) 100vw, 676px" /></p> <p><b><i>Did you know that you can attend the first session of any of our online or in-person GMAT courses absolutely free? We’re not kidding! </i></b><a href="https://www.manhattanprep.com/gmat/classes/?utm_source=manhattanprep.com%2Fgmat%2Fblog&utm_medium=blog&utm_content=GMAT%20Complete%20Courses%20Plug&utm_campaign=GMAT%20Blog" target="_blank"><b><i>Check out our upcoming courses here</i></b></a><b><i>.</i></b></p> <hr /> <p>‘Ratios?’ You might be thinking. ‘Those are easy. Pretty sure I get those.’</p> <p><iframe src="//giphy.com/embed/4GIvR6cmYs8jC" width="480" height="361" frameBorder="0" class="giphy-embed" allowFullScreen></iframe></p> <p><a href="//giphy.com/gifs/bye-abandon-thread-4GIvR6cmYs8jC"></a></p> <p>Wait. Let’s pretend I am the eccentric owner of a pet store, and I sell only two types of pets: rabid donkeys and three-legged mountain lions. In my store the ratio of donkeys to lions is 3:7. What do you know?</p> <p>‘….That for every 3 donkeys you have 7 lions. Thanks for all the information, weird guy, should I get an external hard-drive so I can back all that up?’</p> <p><span style="font-weight: 400;">Okay, drop the sarcasm, reader of my invention. </span><b>When the GMAT gives you a ratio, it actually contains a boatload of information. </b><span style="font-weight: 400;">Take a second and brainstorm what else you can figure out about this pet store. Anything at all.</span><br /> <span id="more-12932"></span></p> <p>You didn’t do the exercise, but whatever, I’ll continue anyway.</p> <p>How about at the simplest level: I have more lions than donkeys. That can be useful information!</p> <p><span style="font-weight: 400;">How about this: what fraction/percent of my animals are donkeys? (Careful, if you say 3/7, you fell for the most common ratio trap. Ratios compare parts to parts. To get a fraction or percent of the </span><i><span style="font-weight: 400;">total</span></i><span style="font-weight: 400;">, we must first </span><i><span style="font-weight: 400;">add these parts</span></i><span style="font-weight: 400;">. My </span><i><span style="font-weight: 400;">relative total </span></i><span style="font-weight: 400;">is the sum of the </span><i><span style="font-weight: 400;">relative parts</span></i><span style="font-weight: 400;">: in this case 3+7=10).</span></p> <p>So my fraction/percent that are donkeys: 3/10, or 30%. 70% of these animals are lion. So when I’m given a ratio of the parts, I can tell you percentages of the total. Also I can give you relative percents between animals themselves. I have 133% more lions than donkeys, which is the same as saying 233% the number of donkeys is my number of lions. The inverse of that: I have approximately 57% fewer donkeys than lions (4/7 is approximately 57%), which is the same as saying the number of donkeys I have is 43% the number of lions.</p> <p><span style="font-weight: 400;">Note that we’re working from ratio to these percentages, but you can also work from the percentages to the ratio. When I’m given a relative value between items, I can typically tell you </span><i><span style="font-weight: 400;">every</span></i><span style="font-weight: 400;"> relative value between them.</span></p> <p><span style="font-weight: 400;">Another question: which of the following could be the number of donkeys in my pet store?</span></p> <p>-82<br /> <span style="font-weight: 400;">-83<br /> </span><span style="font-weight: 400;">-84<br /> </span><span style="font-weight: 400;">-85<br /> </span><span style="font-weight: 400;">-86</span></p> <p>Because we’re dealing with discrete (that is, countable in whole number) items (let’s pretend my pet store isn’t so eccentric as to sell half-donkeys), just by knowing the ratio, we know something about the possible number of donkeys. And lions. And the total number of animals.</p> <p><b>Remember, whenever you have a ratio, you also have an ‘unknown multiplier’—some value that you can multiply each </b><b><i>relative value</i></b><b> of the ratio to get the </b><b><i>actual values</i></b><b> of those items.</b><span style="font-weight: 400;"> Let’s call the unknown multiplier ‘m’ (I avoid using x for the multiplier, because a lot of students will solve for ‘x’ and forget they aren’t done with the problem; the GMAT never asks for the multiplier itself, but they use it as a trap answer sometimes).</span></p> <p><span style="font-weight: 400;">So the ratio in </span><i><span style="font-weight: 400;">actual</span></i><span style="font-weight: 400;"> values is 3m:7m (which simplifies to the 3:7 we’re given).</span></p> <p>Now let’s consider the possibilities for this ratio. The simplest case is we have 3 donkeys, 7 lions, and 10 total animals. That is, the unknown multiplier is 1. This… never happens on the GMAT. It’s a great idea to pick those values on a problem that can be solved with smart numbers, but otherwise, just realize the unknown multiplier is virtually never ‘1’. What other possibilities might we have?</p> <p><img decoding="async" class="alignnone size-full wp-image-12933" src="https://cdn2.manhattanprep.com/gmat/wp-content/uploads/sites/18/2017/01/ra-1-image-1.png" alt="Manhattan Prep GMAT Blog - The Knowledge Trove that Is a GMAT Ratio by Reed Arnold" width="544" height="173" srcset="https://cdn2.manhattanprep.com/gmat/wp-content/uploads/sites/18/2017/01/ra-1-image-1.png 544w, https://cdn2.manhattanprep.com/gmat/wp-content/uploads/sites/18/2017/01/ra-1-image-1-300x95.png 300w" sizes="(max-width: 544px) 100vw, 544px" /></p> <p><span style="font-weight: 400;">etc. etc. etc.</span></p> <p>What do you notice?</p> <p>The donkeys are in multiples of 3, the lions in multiples of 7, and the total in multiples of 10. In the question above, the only choice that was a multiple of 3 is 84.</p> <p>“BUT WAIT! THERE’S MORE!”</p> <p>Okay, Billy Mays, calm down.</p> <p>Which of the following could be the positive difference between the number of donkeys and the number of lions?</p> <p><span style="font-weight: 400;">-42<br /> </span><span style="font-weight: 400;">-46<br /> </span><span style="font-weight: 400;">-50<br /> </span><span style="font-weight: 400;">-64<br /> </span><span style="font-weight: 400;">-66</span></p> <p>Let’s look at the chart again, replacing the ‘total’ column with ‘difference’:</p> <p><img decoding="async" loading="lazy" class="alignnone size-full wp-image-12934" src="https://cdn2.manhattanprep.com/gmat/wp-content/uploads/sites/18/2017/01/ra-1-image-2.png" alt="Manhattan Prep GMAT Blog - The Knowledge Trove that Is a GMAT Ratio by Reed Arnold" width="583" height="187" srcset="https://cdn2.manhattanprep.com/gmat/wp-content/uploads/sites/18/2017/01/ra-1-image-2.png 583w, https://cdn2.manhattanprep.com/gmat/wp-content/uploads/sites/18/2017/01/ra-1-image-2-300x96.png 300w" sizes="(max-width: 583px) 100vw, 583px" /></p> <p><span style="font-weight: 400;">The unknown multiplier </span><i><span style="font-weight: 400;">also</span></i><span style="font-weight: 400;"> applies to the </span><i><span style="font-weight: 400;">difference </span></i><span style="font-weight: 400;">between the parts of your ratio! 7-3=4, so our final difference must be a multiple of 4. The only answer that was a multiple of 4 was 64. </span></p> <p>Also, we can use a ratio to set up an equation (useful in solving a system of equations). If the ratio of D:L is 3:7, then D/L = 3/7, or 7D=3L (this last one is the equation the GMAT can give you when it’s trying to hide that it’s showing you a ratio).</p> <p><i><span style="font-weight: 400;">Your</span></i><span style="font-weight: 400;"> job is to recognize which facts are useful in the problem you’re solving, but in order to do that it’s important to understand what information is even available to you when the GMAT gives you what looks like a boring two or three number ratio.</span></p> <p><span style="font-weight: 400;">Now. I’m going to get back to wiping foam off this donkey’s mouth. Happy studying. ?</span></p> <p><iframe loading="lazy" src="//giphy.com/embed/xT8qBhUUelhfFfl7Py" width="480" height="270" frameBorder="0" class="giphy-embed" allowFullScreen></iframe></p> <p><a href="//giphy.com/gifs/fallontonight-xT8qBhUUelhfFfl7Py"></a></p> <hr /> <p><b><i>Want some more GMAT tips from Reed? Attend the first session of one of his <a href="//www.manhattanprep.com/gmat/classes/?utm_source=manhattanprep.com%2Fgmat%2Fblog&utm_campaign=GMAT%20Blog&utm_medium=blog&utm_content=Reed%20Arnold%20Upcoming%20GMAT%20Courses%20Link#instructor/366" target="_blank">upcoming GMAT courses </a>absolutely free, no strings attached. Seriously.</i></b></p> <hr /> <p><em><strong><a href="//www.manhattanprep.com/instructors/reed-arnold/?utm_source=manhattanprep.com%2Fgmat%2Fblog&utm_campaign=GMAT%20Blog&utm_medium=blog&utm_content=Reed%20Arnold%20Bio%20Link" target="_blank">Reed Arnold</a><a href="//www.manhattanprep.com/instructors/reed-arnold/?utm_source=manhattanprep.com%2Fgmat%2Fblog&utm_campaign=GMAT%20Blog&utm_medium=blog&utm_content=Reed%20Arnold%20Bio%20Link" target="_blank"><img decoding="async" loading="lazy" class="alignleft wp-image-12946 size-thumbnail" src="https://cdn2.manhattanprep.com/gmat/wp-content/uploads/sites/18/2017/01/reed-arnold-150x150.png" width="150" height="150" /></a> is a Manhattan Prep instructor based in New York, NY.</strong> He has a B.A. in economics, philosophy, and mathematics and an M.S. in commerce, both from the University of Virginia. He enjoys writing, acting, Chipotle burritos, and teaching the GMAT. <a href="//www.manhattanprep.com/gmat/classes/?utm_source=manhattanprep.com%2Fgmat%2Fblog&utm_campaign=GMAT%20Blog&utm_medium=blog&utm_content=Reed%20Arnold%20Upcoming%20GMAT%20Courses%20Link#instructor/366" target="_blank">Check out Reed’s upcoming GMAT courses here.</a></em></p> <p>The post <a rel="nofollow" href="https://www.manhattanprep.com/gmat/blog/the-knowledge-trove-that-is-a-gmat-ratio/">The Knowledge Trove that Is a GMAT Ratio</a> appeared first on <a rel="nofollow" href="https://www.manhattanprep.com/gmat">GMAT</a>.</p> ]]></content:encoded> </item> </channel> </rss>