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This series of emails and PMs focuses on situations that many Test Takers face during their studies. The names of the original posters have been changed to protect their identities.
System Algebra Rules
Hi Rich,
I have a question about systems of linear equation w/ n variables - you need n distinct linear equations to be able to solve for each variable. My question is does each distinct linear equation have to include every one of the n variables? What if you have a system of linear equations with 3 variables (x, y, and z) and 3 distinct linear equations where the 1st equation includes all variables (x, y, and z) in the system, but the 2nd and 3rd equations only include 2 of the 3 variables?
Would it still be possible to solve? Is there a general rule associated with this?
PE
Hi PE,
The 3 equations do NOT need to include all 3 variables.
Here's a simple example:
A + B + C = 6
A = 1
B = 2
Here are 3 variables and 3 unique equations, but each equation does NOT include all 3 variables; notice that you can still solve for each variable.
It's worth noting that sometimes a “system" question does NOT require you to solve for each variable, so you might have fewer equations than you THINK you need (but you can still get the correct answer):
For example:
D + E + F = 9
D + E = 5
What is the value of F?
Here, you don't need 3 distinct equations to answer the question.
Improving Quant in a Limited Amount of Time
Rich,
I recently took my GMAT for the first time, and did very well in Verbal but I need some help in Quant. I was wondering if you had any advice on how to take my Quant score from a 39 (49%) to an 80th percentile score. I did the Official Guide 13 and all of the Quant practice questions in the Gmat Prep software (& I have a tutor). I'm retaking the test in a month.
Koo
Hi Koo,
These days, the 80th percentile is just above a Quant Scaled Score of 49. To score at THAT level, you have to eliminate almost all of your silly mistakes, be very strong at Data Sufficiency and have proper pacing skills (so that you're not guessing on a bunch of questions at the end of the section).
One month is probably not enough time for you to make the necessary changes to how you approach the Quant section and score a Q49. With a Q39, you have some gaps in your knowledge, you’re not using the proper Tactics and you’re making little mistakes throughout the section. Improving ALL of those areas will almost certainly take more than one month’s time.
You CAN make some changes to pick up some points though. Take a good look at the questions you're getting wrong, identify the errors/mistakes and try to fix those specific problems. Take a good look at how you're organizing your work and how quickly you start working and you might be able to improve your speed (and by extension, your pacing).
You EARN The Score You Receive On Test Day
Rich,
I’m aiming for a 700+ on the GMAT. There are a variety of books that I’m thinking about buying – can any of them get me to a 700+ and a 45+ raw score on the Quant side on its own?
Ere
Hi Ere,
You bring up two different issues – scoring 700+ and score Q45+. Depending on how well you perform in the Verbal section, you might not need a Q45+. It’s also possible that you would actually need much higher than a Q45 to hit 700+ (again, depending on your Verbal Scaled Score).
There are a variety of books/courses/etc out there that can help you to hit your maximum personal score, BUT none of those resources is a "magic wand" - you're not suddenly going to hit a 700+ just because you read a book.
Many Test Takers use a variety of resources during their studies, so you likely have to think in larger-scale terms. The Official GMAT gives you a score that you EARN, so plan to work hard and keep earning. If your current resources aren't working for you, then you should be able to figure it out pretty quickly and then invest in some new resources.
GMAT assassins aren't born, they're made,
Rich
