An “Undesired” Approach to GMAT Probability

An “Undesired” Approach to GMAT Probability

By: Rich Zwelling, Apex GMAT Instructor Date: 11th March, 2021 In our last post, we discussed a solution for the following question, which is a twist on an Official Guide GMAT probability problem: Xavier, Yvonne, and Zelda individual probabilities for success on a...
Combinations with Restrictions

Combinations with Restrictions

By: Rich Zwelling, Apex GMAT Instructor Date: 4th March, 2021 In our previous post, we discussed how GMAT combinatorics problems can involve subtracting out restrictions. However, we discussed only PERMUTATIONS and not COMBINATIONS. Today, we’ll take a look at how the...
Permutations with Restrictions

Permutations with Restrictions

By: Rich Zwelling, Apex GMAT Instructor Date: 2nd March, 2021 So far, we’ve covered the basics of GMAT combinatorics, the difference between permutations and combinations, some basic permutation and combination math, and permutations with repeat elements. Now, we’ll...
What Happens When Permutations Have Repeat Elements?

What Happens When Permutations Have Repeat Elements?

As promised in the last post, today we’ll discuss what happens when we have a PERMUTATIONS situation with repeat elements. What does this mean exactly? Well, let’s return to the basic example in our intro post on GMAT combinatorics: If we have five distinct paintings,...
An Intro to Combination Math

An Intro to Combination Math

Last time, we looked at the following GMAT combinatorics practice problem, which gives itself away as a PERMUTATION problem because it’s concerned with “orderings,” and thus we care about the order in which items appear: At a cheese tasting, a chef is to present some...
A Continuation of Permutation Math

A Continuation of Permutation Math

Review of Example From Last Post Last time, when we started our discussion of GMAT Combinatorics, we gave a brief example of GMAT permutations in which we had five paintings and asked how many arrangements could be made on a wall with those paintings. As it turns out,...