Analysing Math Practice Problem

[javian.malcolm]

Hello

I hope this is the appropriate place to ask this question.

After reading Stacy's insightful article on "How to analyze a Practice Problem", I realized I am guilty of just working questions and moving on, and am now motivated to try and get the most out of my study. However, I am having a problem CATEGORZING a practice problem and was wondering if someone would kindly tell me if I am on the right track.

To illustration my concerns, I've chosen to use Check Your Skills #4 from the "Formulas and Function" chapter of the Algebra Guide

When Tom moved to a new home, his distance to work decreased by 1/2 the original distance and the constant rate at which he travels to work increased by 1/3 the original rate. By what percent has the time it takes Tom to travel to work decreased?

*After working out the the question*

Analysis

Topic: Given the change in two variables affecting a quantity, determine the new value of a quantity

Sub-Topic: Percentage Decrease

Process/Technique to solve: Determine the original value of the quantity and the new value of the quantity given the change.

Comprehended symbols etc. : Yes

Facts/Knowledge being tested: Rate = distance/time, %decrease = change/original x100

__________________________

My Concerns:

For example, for Topic should I have put "Question with unspecified amounts" or for Process/Technique should I have put "Target method/Algebra". In general, I'm not sure if I'm on the right track.

Any help would be appreciated.

Thanks in Advance
Javian

[StaceyKoprince]

I think your analysis looks great. There isn't a pre-prescribed formula or set of things to use - as long as the words accurately describe the situation and make sense to you, you're good.

It's also the case that more complicated questions often test multiple things, so you may have to make a judgment call about what to label as the main topic - or you may sometimes decide to list two things. That's all fine, too.

In this instance, you could also have put Percentage Decrease as the Topic and not labeled a subtopic - IF you know what "percentage decrease" means (figuring out the change in some quantity over time, which is basically what your Topic currently says), that's fine. If you don't know percentage decrease well enough, then you'd of course want to articulate a description of it, write down the formula, etc.

Keep up the good work!

[javian.malcolm]

Thanks stacy for your reply and encouraging words.

[tommywallach]

Glad to help!

-the MPrep GRE team