## Articles published in Challenge Problem

### A Memorizable List of GMAT Quant Content (Quantent)

Even though there’s no “new math” on GMAT Quant, there is still a ton of content to keep on our radar. And just like the tragic studying for a vocab test, we’ll have to learn 200 different things, even though the test is going to only ask us 31 of those things (because we don’t know which 31 things we’ll get asked on our test day). Read more

### Help! I Can’t Handle GMAT Probability and Combinatorics (Part 3)

Did you know that you can attend the first session of any of our online or in-person GMAT courses absolutely free? We’re not kidding! Check out our upcoming courses here.

In the previous articles in this series, we developed a critical skill for GMAT probability and combinatorics problems: listing out cases. Let’s start by taking another look at the practice problem from the end of the last article. Read more

### Help! I Can’t Handle GMAT Probability and Combinatorics (Part 2)

Did you know that you can attend the first session of any of our online or in-person GMAT courses absolutely free? We’re not kidding! Check out our upcoming courses here.

In the previous article in this series, we introduced two big ideas about GMAT probability and combinatorics:

1. Most people find them counterintuitive.
2. The best way to get past that is to list the possibilities.

In this article, we’ll focus more on #2. How do you list out the possibilities in a GMAT probability or combinatorics problem? Let’s try it on a simple probability problem. Read more

### Help! I Can’t Handle GMAT Probability and Combinatorics (Part 1)

Did you know that you can attend the first session of any of our online or in-person GMAT courses absolutely free? We’re not kidding! Check out our upcoming courses here.

There’s a classic brain teaser called the Monty Hall problem. It’s named after the host of an old-timey TV game show, who used it to confound contestants. He’d present each contestant with three closed doors. Behind one door was a new car, and behind the other two doors were goats.

Monty invited the player to pick one of the three doors. Whichever door the player chose, Monty would then open a different one, revealing a goat, not the car. Then, he would offer the player a choice. If the player wanted, he could switch doors, picking the other unopened door. Or, he could stick with the door he picked in the first place. Whichever decision he made, he would win the prize behind the door he chose. Read more

### Here’s How to do GMAT Unit Conversions Like a Pro

Sometimes the whole point of a specific GMAT problem is to convert between miles and kilometers, or meters and centimeters. In other problems, you’ll need to do a unit conversion as part of a longer solution. It’s easy to mess up unit conversions, and the GMAT writers know this — they include them on the test in order to test your level of organization and your ability to double-check your work. Here’s how to add fast unit conversions to your repertoire of skills.   Read more

### Manhattan Prep’s GMAT® study app is now available!

I am very excited to announce that our new GMAT® study app is available on both iOS and Android!

### Monthly GMAT Challenge Problem Showdown: January 13, 2013

We invite you to test your GMAT knowledge for a chance to win! The second week of every month, we will post a new Challenge Problem for you to attempt. If you submit the correct answer, you will be entered into that month’s drawing for free Manhattan GMAT prep materials. Tell your friends to get out their scrap paper and start solving!

Here is this month’s problem:

If pq, and r are different positive integers such that p + q + r = 6, what is the value of x ?

(1) The average of xp and xq is xr.

(2) The average of xp and xr is not xq.

### GMAT Challenge Problem Showdown: December 23, 2013

We invite you to test your GMAT knowledge for a chance to win! Each week, we will post a new Challenge Problem for you to attempt. If you submit the correct answer, you will be entered into that week’s drawing for a free Manhattan GMAT Prep item. Tell your friends to get out their scrap paper and start solving!

Here is this week’s problem:

A pharmacy must purchase a set of n metal weights, each weighing an integer number of grams, such that all integer weights from 1 to 300 grams (inclusive) can be made with a combination of one or more of the weights. What is the minimum number of metal weights that the pharmacy must purchase?

### GMAT Challenge Problem Showdown: December 16, 2013

We invite you to test your GMAT knowledge for a chance to win! Each week, we will post a new Challenge Problem for you to attempt. If you submit the correct answer, you will be entered into that week’s drawing for a free Manhattan GMAT Prep item. Tell your friends to get out their scrap paper and start solving!

Here is this week’s problem:

A set of n identical triangles with angle x° and two sides of length 1 is assembled to make a parallelogram (if n is even) or a trapezoid (if n is odd), as shown. Is the perimeter of the parallelogram or trapezoid less than 10?