Proportion and Variation are important mathematical concepts. The GRE test takers are required to be proficient and quite handy with the Proportion and Variation techniques because a lot of questions in the exam are based upon them. Usually, there is a secondary and perhaps lengthier way to solve a question, which can be solved within seconds with the help of variation concepts.
Let us take a quick review of the Proportion and Variation theory and try a few GRE practice questions.
If X is directly proportional to Y, then as X increases Y also increases proportionally. For example, the relationship between speed, distance and time, speed is directly proportional to distance when time is constant. This means that the distance a body travels will double if the speed becomes twice. Well, isn’t it common sense? Obviously if you move faster, you will discover greater distance in the same time period. So, you see, people have a way to complicate things in the name of formulating apt theories!
Variation is the same thing as above, with the only exception that the ratio is not constant. In proportion, if one quantity doubles, the other one doubles as well. In Variation, one quantity can increase by three times, four times or only marginally, in response to an increase in the other related quantity.
The variation between the two quantities is determined by X = KY where K is the constant of variation. Continue reading