The Speedy Road to Insufficiency
Here’s another quick tip for those of you still struggling with the pitfalls of Data Sufficiency. Let’s take a look at the following Official Guide DS problem: If p and q are positive integers and pq = 24, what is the value of p? (1) q/6 is an integer (2) p/2 is an …
Intuition and Common Sense on Geometry DS Questions
“Who cares?” That should be the operative question on your mind as you tackle Data Sufficiency problems. Here’s what I mean: Suppose I ask you the question “What is x?” I then give you a statement that says “2,346.456 x + 87,234 = 912,347π”. Is the statement sufficient? “Yes,” you’d …
Tips for Comparing Fractions on the GMAT
When discussing fractions, I often find a very interesting area of confusion among students. I’ll ask them to compare, for example, 1/3 and 1/4. Almost everyone correctly answers that 1/4 is smaller. “How do you know?” I’ll ask. And this is where the confusion starts. More often then not, most …
Filling in Your Chart: A Data Sufficiency Primer
In last week’s post, I gave the following Data Sufficiency problem to be solved using a chart: A certain zoo has 288 mammals, 25 percent of which are female. What percent of the mammals in the zoo were born at the zoo? (1) The number of male mammals that were …
To Venn or Not to Venn? Depends on the Question.
Many students like to ask me the following question when dealing with overlapping sets problems: “Which are better? Venn diagrams or charts?” I’ve found that students like to ask because every student has a personal preference. Some don’t want to deal with Venn Diagrams because labeling them can get confusing …
Two Shortcut Formulas for Set Problems
If you’re one of those people who goes crazy over overlapping sets problems, this post is for you. Oftentimes, Venn Diagrams are the way to go on these problems, and I highly recommend that you master them in our GMAT course. However, if you’re more formula-oriented, there’s a handy shortcut …
More Fun with Weighted Averages
In last week’s post, I discussed how weighted averages are often tested conceptually and thus show up on Data Sufficiency problems. However, even when weighted average problems appear on the more results-oriented Problem Solving questions, this conceptual understanding can be mighty handy. As I said in a previous post, the …
What the Heck is a “Weighted Average”?
If you’ve done some GMAT preparation already, you’ve likely come across the concept of “weighted averages.” But what does that term really mean? In short, the term “weighted” is simply meant to indicate that separate groups of numbers have different numbers of elements and thus should be weighed differently. Let’s …
Quick GMAT Mental Math: Averages
I run the risk of sounding like a hypocrite here. I’m often fond of telling my students that the GMAT is a reasoning test, not a speed calculation test. (I say this to assuage their fears after I break the bad news that no calculators are allowed. I tell them …
How to Approach Rate Problems on GMAT Quant, Part II
Last week, I focused on rate problems involving speed (if you’re looking to the answer to last week’s challenge question, scroll down to the end of this post!). This week, I’m going to shift to work-rate problems, which some students find even more challenging. You know these problems… the ones …
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