Many quantitative questions have variables in both columns. While your first instinct may be to work algebraically, this strategy is not always best. Often the fastest way to a solution is by plugging in different values to see which column is greater. Developing a sense of when to plug in and when to solve algebraically […]

# Archive | Plugging In

## GRE Quantitative Comparison Tip #2: Striving for Equality

In my previous post, we examined the pros and cons of two approaches for tackling Quantitative Comparison (QC) questions involving variables. Those approaches are: Apply algebraic techniques Plug in numbers In today’s post, we’ll examine a useful strategy that can increase the effectiveness of the plug-in-numbers approach. To set up today’s strategy, please consider the […]

## GRE Math Review Quiz: Plugging In

I’ve compiled 7 practice problems (some old, some more recent) from math posts on our blog that are great practice for using the “plugging in” strategy. If you’re already familiar with the approach, test yourself with these problems to review the strategy– it’s a method you’ll definitely be able to use for several different question […]

## GRE Math Strategies – When to Plug-In

See if you can finish this rate problem in less than two minutes. A transcontinental jet travels at a rate of x – 100 mph with a headwind and x + 100 mph with a tailwind between Wavetown and Urbanio, two cities 3,200 miles apart. If it takes the jet 2 hr 40 minutes longer […]

## Part II: Does Plugging in Work on GRE Quantitative Comparison?

Can Plugging In Work on Quantitative Comparison? Plugging in, a great strategy on problem solving, can also be very effective on the current and new GRE’s quantitative comparisons. The ground rules for plugging in on quantitative comparison, however, are a little different. But before I explain how, why don’t you try to crack the following problem. Xyla […]

## Part I : The Power of Plugging In – GRE Math Techniques

With BBQ season nearing, it’s time for hotdogs and burgers. Well, sort of. Try the problem below. A concession stand sells either hotdogs for $1.75 each or hamburgers for $4 each. If Charlie buys a total of 9 items from the concession stand for a total of 27 dollars, then how many hotdogs did he […]

## New GRE Question Type — The Empty Box (aka Numeric Entry)

Two trains starting from cities 300 miles apart head in opposite directions at rates of 70 mph and 50 mph, respectively. How long does it take the trains to cross paths? This is a classic problem that sends chills up students’ collective spines. I’m now going to add another bone rattling element: The Empty Box. […]

## GRE Math Strategies Part II of VI: Plug In (Substitution) Method

The correct answer to a math question is always among the five answer choices. So, for problems with simple equations or answers, it is often quick and easy to substitute each answer choice into the question (the mathematical expression or narrative) and see which one works. This strategy works best when a symbolic expression (like […]