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# Archive | Algebra

Learn this powerful math trick for GMAT Problem Solving questions.  First, try these two practice GMAT Quantitative section Problem Solving questions. 1) Bert left the house with N dollars.  He spent 1/4 of this at the hardware store, then \$7 at the dry cleaners, and then half of what was left at the grocery store.  […]

## Algebra on the GMAT: How to Factor

Master this fundamental algebraic skill which you will need on test day!  First, try these practice problems. 1) (A) (x – 4)(x + 6) (B) (x + 4)(x – 6) (C) (x – 4)(x – 6) (D) (x – 2)(x + 12) (E) (x + 2)(x – 12) 3) If , then |a| + |b| […]

## FOIL on the GMAT: Simplifying and Expanding

First, try this question: 1) (A) (B) (C) (D) (E) If you find this problem relatively easy, probably most of this post will be for you as well.  If this problem makes your head spin, you have found exactly the post you need.   Monomials and Binomials First, a review of terms.  In algebra, any […]

## GMAT Solution and Mixing Problems

Attention, mad scientists out there!  Consider these two practice questions.   1) A scientist has 400 units of a 6% phosphoric acid solution, and an unlimited supply of 12% phosphoric acid solution.  How many units of the latter must she add to the former to produce a 10% phosphoric acid solution? (A) 200 (B) 400 […]

## Simplifying Radical Expressions on the GMAT

Practice questions Let’s start out with a couple practice questions. 2) What is the length of the diagonal of a square with area 48? The geometry of those questions is not too difficult, but the trick is how to handle those radicals.  If that befuddles you, this is just the post for you.   Distributing […]

## Scale Factors on the GMAT: Percent Increases and Decreases

First, try these practice questions:   1) Every length in a 45°-45°-90° triangle increases by 20%.  By what percent does the area of the triangle increase? (A) 20% (B) 25% (C) 40% (D) 44% (E) 80% 2) At a certain pizza parlor, the diameter of a large pizza is 40% larger than the diameter of […]

## GMAT Math: Rate Questions

Learn to master this common type of GMAT word problem!   Speed Rate is another word for speed, and the equation for this is D = RT (which some people remember as the “dirt” equation).  D = distance, R = rate (a.k.a. speed, a.k.a. velocity), and T = time.  One common source of errors is […]

## GMAT Work Rate Problems

First of all, consider these three GMAT like questions.  Try them on your own before reading the post.  I will show solutions to these practice questions at the end of this post. 1) Running at the same rate, 8 identical machines can produce 560 paperclips a minute.  At this rate, how many paperclips could 20 […]

## GMAT Quant: Thoughts on Remainders

For a start, give these problems a try.  A complete explanation will come at the end of the discussion.   1) When positive integer N is divided by positive integer J, the remainder is 14.  If N/J = 134.08, what is value of J? (A) 22 (B) 56 (C) 78 (D) 112 (E) 175 2) […]

## GMAT Quant: How to Solve Two Equations with Two Variables

Fact: If you have two variables and only one equation, in general you will not be able to solve for the individual values of the variables.  You need two separate equations in order to solve for the individual values of each of two variables. (This fact is crucially important on the GMAT Quantitative Section.) More […]