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Collapsing Probabilities in GMAT Probability: Part Deux

Collapsing Probabilities: Part Deux — for Part Un, Click Here This one I’m only doing with the “Collapsing Probabilities” technique. You’re welcome to do it by making your choice first, then multiplying by the number of potential choices. It’s just that I won’t. You can e-mail me if you need your hand held. Here’s the … Read More

Collapsing Probabilities in GMAT Probability

Collapsing Probabilities in GMAT Probability Unsurprisingly, there’s more than one way to look at this phenomenon. Let’s take a look at this straightforward case… Bag 1 contains forty marbles numbered consecutively from 11 to 50. Bag 2 contains fifty marbles numbered consecutively from 41 to 90. If one marble is selected from each bag, what … Read More

GMAT Probability: Number of Distributions x Probability per Distribution

GMAT Probability and Number of Distributions x Probability per Distribution The Independent Probability Case for GMAT Probability Now, let’s go back to the example from the previous page, which we can rephrase as this:If a coin is flipped five times, what is the Probability that it will land on Heads only once?That gives us a … Read More

“At Least” Problems in GMAT Probability

“At Least” Problems in GMAT Probability Hey, remember how all the Probabilities have to be fractions less than one? I mean, after all, it’s reasonably rare for there to be a greater than 100% chance that something will happen. The other thing to bear in mind is that a full Probability–anything that is forgone conclusion–is … Read More

GMAT Combinatorics: How to Understand GMAT Factorials (also useful for Probability!)

GMAT Combinatorics: How to Understand GMAT Factorials — the Three-Question Method (also useful for GMAT Probability!) If we don’t get the concept of Factorials straight, the rest of this–Permutations and Combinations, quite a lot of advanced GMAT fatoring, etc.–is never going to work. How to Think About GMAT Factorials in a Broad Sense The idea … Read More

The Real World versus GMAT Critical Reasoning

                                        There isn’t really much relationship between GMAT Critical Reasoning and the Real World GMAT Critical Reasoning questions are extremely tightly-constructed little logic bombs that have nothing to do with the Real World. While it’s not pleasant to have to say this, I think it’s … Read More

How to Analyze GMAT Quant Questions Properly PART II

CONSISTENTLY ASK YOURSELF: “Am I spinning my wheels?” Remember, that means doing things that won’t get you to the answer any faster. Are you calculating something that won’t yield one of the five answer choices? That’s not to say that the GMAT is giving you wrong information, but rather that the answer choices restrict your … Read More