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

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