For about a year, I always used the same method to solve the following GMAT problem:
How many liters of water must be evaporated from 50 liters of a 3 percent sugar solution to get a 5 percent sugar solution?
“This is simple percentages,” I would say. “Just start by taking 3% of 50 liters, which is 3 over 100 times 50, which comes out to 1.5 liters sugar…”
But one day, teaching this same quantitative problem, a student’s hand shot straight up. “Yes, James?” I said. (That wasn’t his real name, by the way, but it will do.)
“Eli, who cares about the sugar?”
I paused. “Well, the sugar will help us figure out the solution.”
“But you don’t need it!” James explained. “I’ve been a chemical engineer for years, so I do this problem all the time. The sugar is a constant. The amount of sugar doesn’t change, … Read full post
I want you to think back to when you were in grammar school (strange how often the test for business school has us thinking about grammar school). Specifically, I want you to think about gym class and every time you needed to pick teams. For purposes of today’s discussion, let’s say we are picking a baseball team from the students in class. Now I realize that for some of you this was a traumatic experience, and GMAT teachers are no exception to that – we are not particularly notable for our athletic prowess. However, this scenario can help you understand a difficult question type on the GMAT – permutation problems.
A permutation problem will ask you to determine the number of ordered subsets of a certain size that exist in a group. If we move away from GMAT speak, this means permutations will occur when you must perform two actions. … Read full post