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Posted on
Feb 2019

If you’re doing math on the GMAT, watch this.


I want to discuss one of the core tenents of Apex’s quantitative philosophy on the GMAT, and that is that “If you’re doing math, you’re doing something wrong.” This means, if you find yourself doing math, that’s a signal from the exam that you’re using a sub-optimal solution path. And by math I don’t mean any calculation whatsoever, but any calculations that aren’t reasonable, that don’t come out easily, neatly and cleanly, once you’re well practiced with mental math. So it’s not that we’ll never do a calculation, but every calculation we do should be deliberate and should be smooth.

Let’s go a little deeper into this, because it’s a really important concept. Many, many people preparing for the GMAT spend way too much time worrying about the math, being freaked out about the math and on the exam doing the math. The applied mathematical solution path is the most over used solution path on the quantitative side of the GMAT. Particularity among engineers, and with people who do a lot of self prepping, they look to the back of the book or look to their previous experience as students and they get caught up in the idea that their answer needs to be precise. This gets in the way of us using our estimation solution path or one of the other higher solution paths that get us to the correct answer much more quickly.

How do we know that math is not what the GMAT wants us to do? It’s quite simple. If the GMAT was the referendum on how well you can do mental math, then the scores would reflect your ability to do so. MBA programs at top business schools would be filled with people with extraordinary, almost savant like mental math abilities. We know this isn’t the case.

Actually, as we improve on our mental math, we get diminishing returns with it, so we see a lot of clients getting up to the 70th, 80th, or 90th percent level even, on the quantitative side of things and then, all of a sudden they plateau; they can’t get any higher. The reason is they are so focused on the math they are missing the bigger logical reasoning picture or the structure of quantitative problems that doesn’t rely on doing math that allows both quick and accurate solutions.

While math has it’s place, we want to be sure that we’re not putting it on a pedestal, and that when we’re performing computations, we’re doing so with great deliberation, with great intentionality, and that we have a very good reason for doing any computation we’re doing. If you find yourself diving into the equation or doing a lot of processing, stop; put a hard stop on it. Say “Wait a minute, there must be a better way to do this.” Or, another option is that sometimes you make a basic processing error early on and that leads to ugly numbers and heavier duty math. But you should never, never, never be multiplying decimals out to the fourth decimal. That sort of math is the true trigger, the true signal, that there’s a better way to solve the problem. When you’re self prepping, this is what you want to look for so by the time you get to the exam, you’re not catching yourself doing math, but you’ve already incorporated it into your process, the fact that math shouldn’t be your default. So, remember, guys, if you’re doing math, you’re doing something wrong and you can take this one to the bank.

Hope this helps and I’ll see you guys again soon.

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Posted on
Feb 2019

Profit & Loss Problem Form

The profit and loss problem form or P&L problem form that this problem fits into
is one that has very strong DSM’s into mathematics. Here we are tempted to do the math in part because that’s so easy, it’s so available to us and this is characteristic of a mid-level arithmetic problem where there’s some shifts and shimmies but overall it’s a fairly straightforward problem that utilizes no more than the four basic operations. So on the one hand this is pre-algebra or even sort of grade school math, on the other this makes the solution path much
more elusive.

So of course we can follow the math. We can add up all the costs, five thousand plus two dollars, times twenty thousand and then contrast that with the revenue that comes in which is
twelve times twenty thousand. But thenwe’re left with the ugly division
problem that brings us to the profit per t-shirt, and this is where the GMAT
sticks us.

So instead of handling this in aggregate it’s strongly preferable to handle it with a higher level solution path. Let’s take a look at a few:

One way to do this is to distribute the fixed cost over the cost per t-shirt and this is actually a lot easier than it seems, twenty thousand t-shirts, five thousand dollars, five over twenty is one-quarter, therefore it costs one-quarter per t-shirt in addition to the two dollars in variable cost, and so twelve minus two is equal to ten dollars, minus one quarter is equal to nine dollars and
seventy-fivecents. It’s sitting right there for us in literally a moment.

We can also use a graphic equalization method in order to get to the same conclusion. If the numbers were more complicated, understanding that that shift is one-quarter down, that is the fixed cost is one-quarter down then we know we’re looking for something that ends in a seventy-five cents. That allows us to eliminate all the answer choices or at least all the answer choices that don’t end in 0.75 and then we can use scale to determine that 9.75 is the correct answer.

There are more complicated versions of this problem form, in particular I’d encourage you to explore being told that the t-shirt company is breaking even and then determining the amount of variable costs or fixed cost that’s there or even the production run. Similarly, you can be given a target profit or loss, the break-even just being the zero, so it’s a bit easier and have to reverse engineer the relationships.

Once again, this doesn’t have to be done algebraically as you begin to appreciate the subtlety of the ratio between costs production run and total P&L all of these problems should be simplified and should be very straightforward.

Find more video’s on the Apex GMAT YouTube channel.

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Feb 2019

Six Things Most GMAT Preppers Get Wrong

I’m Mike Diamond Head Instructor for Apex GMAT, here to talk about the top six things most GMAT preppers get wrong.

1.Thinking that a correct answer means you’re done with the problem.
When you arrive at a correct answer during GMATprep, that should mark the beginning of your preparation on the problem, not the end of it. There are almost always better solution path’s that are more time efficient, that work better with the way your brain engages the problem, or that will add understanding either to the content or more importantly to the underlying structure of the examination. So when you write a correct answer look for alternative solution paths, look for shortcuts and give yourself the latitude to explore. Moreover, try to identify what permitted you get to get the problem correct in the first place. A lot of times people focus much more on the problems they get wrong; on what they’re doing wrong than on what they’re doing right and what you’re doing right can often inform those problems where you are struggling. So remember once you arrived at the correct answer, that’s your starting point.

2. Overusing practice tests.
Practice exams are a crucial part of GMAT preparation, but they’re often misused and overused. Most people use a practice exam to see how they’re doing, but being focused on your score is absolutely the wrong way to approach the GMAT. Rather, you want to be focused on your process and if your process is tight, if your process is correct then the score is going to take care of itself. Practice tests are best used for a number of reasons, none of which have to do with your score. They can be used to calibrate your timing decisions. They can be used to identify weak points in your conceptual understanding, and they can be used to identify where you DSM, default solving mechanism, back into old time consuming and unconstructive solution pathways. So, the next time you have an urge to do a test remember that this is going to rob you of two to three hours of valuable prep time because when you’re doing a practice test, you’re not learning, you’re doing.

3. Caring about your score.
I know it’s counterintuitive, you want that 700-plus score, it’s all you think about, it haunts your dreams, and yet caring about your score is the quickest way to a test anxiety problem and it’s actually entirely unconstructive. Rather, you need to focus entirely on your process and let the score handle itself. Imagine you’re running a race and you’re running as fast as you can, whether you’re a super fit marathon runner or a total couch potato, you can only run as fast as you can and the time on that race is going to reflect that. So don’t sweat the score, sweat your fitness and understand what things you can do to improve your GMAT fitness and the score will take
care of itself.

4.Studying under a time constraint.
Time trials are really important as you mature in your GMAT progress but at the start, you want to focus on the mastery of skills in an un timed environment and only once you’ve achieved mastery try to do them ever more quickly. By focusing on the time before you have the underlying process conquered you end up rushing yourself in a way that exacerbates your mistakes rather than allows you to correct them. So as you’re prepping, focus on total
mastery and understanding first and then and only then begin putting them under
time pressure.

5. Low-yield self-prep.
Most people spendentirely too much time preparing from the GMAT, and they do so because
they’re not getting enough out of their prep time. Does this sound familiar? Okay,
I’m going to do a group of 10 questions, maybe on a timer for 20 minutes and then
afterwards I’m going to look in the back of the book and when I get the problem right I’m going to say,“yeah,” I never have to deal with this problem again. When I get it wrong in going to go a little bit further and normally I’m going to find something that I knew but I sort of forgot and I’ll say, “oh you know what I won’t forget that, I’m going to get that right next time,” but it doesn’t happen that way does it? That’s a very low yielding strategy, instead, you need to become responsible and accountable for your learning and Apex shows you the way to do so by not just being reactive to problems but proactively creating problems of your own.

6. Doing the math.
We have a sayingaround here and you may have heard it on some of our materials or online videos, if you’re doing that you’re doing something wrong.Most of the GMAT quantitative section requires little to no processing and if you’re scribbling tons of stuff on paper it means you’re missing the bigger picture so remember if you’re doing math there’s always a better way!

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