At a very basic level, it doesn't matter. If the business schools require this test, then you have to take it. It doesn't matter why or how the material relates to real life.
A lot of it does not, in fact, relate to business school or what you will do after business school. It's very unlikely that you will ever again have to calculate the area of a circle, for example.
The business schools are interested in two primary things:
(1) Are you serious about b-school? Are you going to work very hard once you actually get to school? You can prove that to them by working very hard now to get a good score on this test.
(2) How good are you at thinking your way through complex, business-decision-making, or what is called executive reasoning?
http://tinyurl.com/executivereasoninghttp://www.beatthegmat.com/mba/2016/02/ ... n-the-gmatThat's what the GMAT is *really* trying to test at heart.
Having said that, there are some skills that will actually be useful for you in b-school and beyond. Fractions, percents, statistics, estimation, reading charts and graphs, what's called "number sense," or the ability to understand what numbers or data mean and to reason with that information.
You also do need to be able to communicate in a clear and relatively sophisticated manner, and most of grammar is about this. You need to be able to think logically and reason analytically (CR), and you need to be able to find the important, big-idea messages in dense and sometimes confusing text (RC).
But, at the end of the day, the answer is just this: if you want to go to a business school that requires the GMAT, then you have to take the test. Everything else doesn't matter!