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One More RTD Table Problem: Average Rates Part 2

If you haven’t been following our series on RTD tables, take a few minutes to catch up: Using Diagrams to Solve Rate Problems: Part 1 Using Diagrams to Solve Rate Problems: Part 2 A Different Use of the RTD Table: Part 1 A Different Use of the RTD Table: Part 2 Using the RTD Table […]

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Using the RTD Table for a Complicated Problem

My last few blog posts have involved rate problems about simultaneous movement. In each of these problems we discovered exactly two travelers who either (1) moved at their own constant rates for the entire time period covered by the story, or (2) moved at their own constant rates  and started and stopped simultaneously. If you’d […]

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A Different Use of the RTD Table: Part 2

Let’s recap where we left off yesterday.  We were working with this diagram: We wanted to solve for Mary’s time, t. In every row the relationship among rate, time, and distance is the same: RT=D. In this diagram the bottom row looks the most promising, since it alone contains only the variable for which we’re […]

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A Different Use of the RTD Table: Part 1

In my last couple of posts (Using Diagrams to Solve GMAT Rate Problems Part 1 and Part 2) I used a Rate-Time-Distance table, (or RTD table) to solve the most common sort of rate problem: a combined-rate problem in which two travelers move in opposite directions simultaneously.  (If you haven’t read those posts and aren’t […]

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GMAT Math: Midpoints and Parallel vs. Perpendicular lines

First, a few practice questions. 1) Line A has the equation 3x + y = 7.  Which of the following lines is perpendicular to Line A? y = 3x + 4 y = –3x – 6 y = (1/3)x – 1 y = (–1/3)x + 2 y = (–7/3)x – 5 2) Line P has […]

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GMAT Sets: Venn Diagrams

Learn this technique to master set questions of GMAT Quant word problem.    Practice questions First, try these challenging practice questions. 1) Of the 80 house in a development, 50 have a two-car garage, 40 have an in-the-ground swimming pool, and 35 have both a two-car garage and an in-the-ground swimming pool.  How many houses […]

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GMAT Math: Special Properties of the Line y = x

The 45º angle Fact: All lines with slopes of 1 make 45º angles with both the x- and y-axes. Conversely, if a line makes a 45º angles with either the x- of y-axes, you know immediately its slope must be . This first fact is true, not only for y = x and y = […]

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