I’ve got another one for you from our 5 lb. Book of GRE Practice Problems, and this one’s serious. I took it from the Advanced Quant chapter. Try it out and then we’ll chat!

 Triplets Adam, Bruce, and Charlie enter a triathlon. There are nine competitors in the triathlon. If every competitor has an equal chance of winning, and three medals will be awarded, what is the probability that at least two of the triplets will win a medal?

(A) 3/14

(B) 19/84

(C) 11/42

(D) 15/28

(E) 3/4

© ManhattanPrep, 2013

Yuck. I’m not a fan of probability in general and this one is particularly annoying. Why? Because they ask for the probability that at least two will win. Most of the time, when a probability question uses at least or at most language, we can use the cool 1 “ x shortcut because there’s only one not-included case.

For example, if I tell you I’m going to flip a coin three times, I might ask you to calculate the probability that I’ll get at least one heads. There’s only one case where I wouldn’t: zero heads. So you can just calculate the probability of zero heads and subtract from 1.

But we can’t do that here, because it’s possible for just 1 twin to win a medal and it’s also possible for zero twins to win a medal. Sigh.

Okay, how are we going to tackle this? Probability is a measure of the number of desired outcomes divided by the total number of possibilities. Let’s figure out the total number of possibilities first.

Take a look at the question again. Is this one of those questions where the order matters? If you don’t win, you don’t win. If you do win, does the question make a distinction between coming in first, second, or third?

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Many a true word is said in jest.—I don’t know, but I heard it from my mother.

I moved to Los Angeles, to a little bungalow in Laurel Canyon, the day before the Northridge earthquake.  Timing is everything, just like on the GRE.  I woke up around 3 in the morning.  Because the bungalow was jumping up and down.  As a stupid easterner, I thought, Oh, it’s an earthquake.  They have them here.  I didn’t know it was The Medium One.  (It was amazing to see the damage—piles of rubble on Ventura Boulevard and in Hollywood, and the I-10 ramp to the 405 fell down.)  As long as I was awake, I decided to go to the bathroom.  The first big aftershock threw me into the door frame.  It’s unsettling not to have a firm foundation under your feet.  You feel out of control and at the mercy of forces larger than you.

And that’s the way students feel about the GRE.  And for the same reason, metaphorically speaking.  In every GRE class I’ve taught, most of the students were bewitched, bothered, and bewildered by the shakiness of their foundation knowledge.  The ground was not firm beneath their feet.  It paralyzed them.  They understood the concepts of the problems and the relevant strategies to employ, but could not then solve the problems in a timely manner, if at all.  Especially on the quant side, the GRE tests a logic system—be precise, don’t assume, pick the choice that must follow.  The arithmetic and algebra are the moral equivalent of reading English.  You would like to be able to take those skills as much for granted as you do reading words.  When I say 7 times 13, you say 91.  Think of it as a rap.  When you see .625, you say 5/8.  Woot.  All seriousness aside, people waste 30 seconds a question in the quant because they don’t know their times tables or squares or the fractional decimal percentage equivalencies.  Or their algebra isn’t smooth and silky.  Think about how much time that uses up during the section.  How do you fix that?  How do you get to Carnegie Hall?  Practice, practice, practice.  That’s a New York joke—LA classes hate it.  Having that mastery frees you to identify the type, the approach, and the traps—to do what has to be done to score well.

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Each week, we post a new Challenge Problem for you to attempt. If you submit the correct answer, you will be entered into that week’s drawing for two free Manhattan Prep GRE Strategy Guides.

Owners of condominiums in a certain community share annual maintenance costs in proportion to their condominium’s share of the total square footage for all community condominiums at the end of the year. In 2011, when total annual maintenance costs were $104,000, the share of these costs for the owner of a 1,000 square foot condominium was $832.  In 2012, several new condominiums were added to the community, increasing total annual maintenance costs by $5,000 from the previous year and total development square footage by 3,600 square feet.

In 2012, what was the share of maintenance costs for the owner of the 1,000 square foot condominium?

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When was the last time you thought that? For me, it was sometime within the past week. I knew that this problem was not beyond my reach! Meanwhile, the clock was ticking away and all I could focus on was the fact that I couldn’t remember something that I should have been able to remember.

That horrible, sinking feeling is universal: we’ve all felt it before and “ unfortunately “ we’re all going to feel it again. How can we deal with this?

Recognize the But! feeling

You almost certainly already know what this feels like, but here’s a longer list of the ways in which this manifests. When was the last time you thought any of these things?

–        But I studied this

–        But I should know how to do this

–        If I just had a little more time, I’m sure I could figure it out

–        I’ve already invested so much time, I don’t want to give up now

–        I’ve been struggling with this for 2 minutes but I really did finally figure out now what I need to do; it’s just going to take me another 1.5 minutes

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We know that carrying around GRE study materials can be a hassle.  Some days you just can’t carry an extra 5 lbs in your backpack/messenger bag /satchel/kangaroo pouch/suitcase.  As such, students often turn to flash cards for convenient, on-the-go studying.

Up to this point our flash cards have only been a vocabulary building tool and over the past year, students have asked that we offer cards for the quant section of the exam.  It seems that students’ commutes were unbearable (or at least less enjoyable) when they didn’t afford a chance to study for the GRE quant section.  Well, fear not, commuters Math Flash Cards are now available! (If you will, please imagine that last sentence being accompanied by the Superman theme.  You know the one; it has the triumphant horn section.)

Our new math flash cards provide math drills for all skill levels and include easy-to-follow explanations to help you build fundamental math skills for the GRE.  You can use these cards as a teaching tool, or for rapid quant drills.  These 500 cards cover a wide variety of quant topics including algebra, geometry, word problems, number properties, and more.  If you are looking for bite-sized math practice, these cards are for you.

I’ve written a lot “ and you’ve read a lot “ about timing already, but I want to address something that I’ve been hearing lately from students particularly those who have been studying for a while and are really struggling to make progress on practice tests.

My best timing was on my very first practice test

I’ve spoken with a few students lately who’ve told me that they felt more comfortable with the timing before they started studying all of this stuff. How is that possible?

Actually, it’s fairly common. Here’s what happens: on your first practice test (before or shortly after you started studying), you know what you don’t know and so it’s much easier to let go of the too-hard questions. Once you start studying, you’ll see something and think, Oh, I studied that! I can get this one! But it turns out that one is still too hard only, this time, you won’t let go when you should. Do that a few times and the whole situation snowballs: you realize you’re behind on time, you start to panic and rush, that causes careless mistakes. Then you get stuck on another because you feel like you’re getting a bunch wrong so you don’t want to get this one wrong too now you’re wasting even more time, and then the section ends with a bunch of guesses or even blank questions.

I’m fine with OG / untimed / with shorter problem sets

I’m sure it’s no surprise to you that you’re better when the timer isn’t ticking. We all are. Unfortunately, the real test is timed, so our untimed performance doesn’t matter. Lots of people also discover that everything’s fine when doing sets out of the Official Guide, especially shorter problem sets. This, again, is to be expected “ it’s easier to keep track of your global time for 5 or 10 questions rather than 37 or 41.

So what do I do?

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Wait, is that a typo? Maybe I meant Confucius, the Chinese teacher and philosopher?

I actually do mean confusion. ; ) Journalist Annie Murphy Paul recently contributed a post to KQED’s Mind/Shift blog: Why Confusion Can Be a Good Thing.

Go ahead and read it “ I’ll wait. It won’t take you more than 5-10 minutes. Take particular note of item 2 on her 3-item list.

Why Is Confusion Good?

Ms. Murphy Paul supports her thesis with an important point: When we don’t know the right way to do something, we open up our minds to many potential paths “ and sometimes an alternate potential path is better than the official path.

We’ve all had the experience of reading an official solution and thinking, Seriously? That’s how you have to do this? only to find a better way on an online forum or via discussion with a teacher or fellow students.

Further, as far as a test like the GRE is concerned, the discomfort inherent in figuring out that best path allows us to determine why a certain approach is preferable. That knowledge, in turn, helps us to know when we can re-use a certain line of thinking or solution process on a different (but similar) question in future.

How Can I Use Confusion To Help My Prep?

Murphy-Paul offers three suggestions (quotes below are from the article; the rest is just me):

(1) Expose yourself to confusing material

On the GRE, you have no choice: you’re going to be exposing yourself to confusing material every day! So I’ll tweak Murphy-Paul’s suggestion slightly: embrace the confusion. Instead of feeling annoyed or frustrated when that feeling of confusion creeps in, tell yourself: okay, I’m on track here. I’m going to figure this out “ and, when I do, I’m going to remember it because my current confusion is actually going to help me remember better once I do know what I’m doing!

(2) Withhold the answers from yourself

What’s the first thing you do after finishing a problem or problem set? If you’re anything like my students, you look at the answer to see whether you got it right. Is that really the best move?
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Each week, we post a new Challenge Problem for you to attempt. If you submit the correct answer, you will be entered into that week’s drawing for two free Manhattan Prep GRE Strategy Guides.

If n is an integer such that (-3)^-4n > 3^{6 “ n}, which of the following is a possible value of n?

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Here are the free GRE events we’re holding this week (All times local unless otherwise specified):

4/8/13– Online- Mondays with Jen– 9:00PM- 10:30PM (EDT)

4/10/13– New York, NY – Free Trial Class- 6:30PM – 9:30PM

4/13/13– New York, NY – Free Trial Class- 2:00PM – 5:00PM

Looking for more free events? Check out our Free Events Listing Page.

Catch up on some of the top grad school tips and news links from the week. Happy Friday and happy reading!

What Graduate Students Should Know About the Sequester (U.S. News Education)

According to U.S. News, admissions criteria will change at some schools due to the sequestration. Find out why it could lead to a decrease in the number of students admitted.

What to Do When You are Accepted to Grad School (About.com)

Congrats to you if you’ve recently opened a graduate school acceptance letter! Now it’s time for some practical advice about what to do next.

Making the Most of Graduate School Advising (U.S. News Education)

This week U.S. News started a series addressing the questions that admitted graduate students often ask as well as information on how the academic advising process works.

You Can Be Busy or Remarkable”But Not Both (Study Hacks)

Here’s a great post that explains the profound difference between being busy and being remarkable. We think you’ll be ready for some down time after this read.

Did we miss your favorite article from the week? Let us know what you’ve been reading in the comments or tweet @ManhattanPrep