How many and what kind of formula's should I be remembering?

[dubc1982]

I'm trying to figure out how many formula's I'm expected to remember for the GMAT. I feel like I have a good handle on most Geometry ones for area, volume, etc., pythag, work, rate, and mean/median/mode. What else should I remember?

Do I need to know quadratic formula (if that's the right name, the fairly complex one that you would use if can't factor equation)? What about standard deviation?

I feel like that what I know should be sufficient, but I'm wondering what else I should be comfortable with?

Also, I feel like I generally have a good handle on all basic math concepts tested, but still struggle, mostly in probability. What other things can I do beyond practicing to improve me Quant. score? I know all the tricks like plugging in and backsolving, and like I said above most concepts.

I feel like I'm missing something, but can't put my finger on it. I've been practicing for about 3 months and have seen some improvement, but not enough. I've reviewed basic concepts, done many practice questions, but am reaching a plateau. Any help?

[VP_Tatiana]

Hi Dub,

The quadradic is a good formula to memorize, though you may only use it once or twice. You will want to factor out your polynomial whenever possible, as that is much cleaner. You don't need to memorize the standard deviation formula, just have an understanding of how it is calculated. SD questions don't require you to compute, but ask things like, "Which has the bigger SD?" which you can solve without computation.

You will want to memorize number properties, such as how to tell if a number is divisible by 3, by 7, etc. Memorize multiplication tables. Memorize commonly appearing fractions (like 1/8, 1/7, etc). Memorize geometry rules, like the proportions of a 30-60-90 or 45-45-90 triangle and the pythagorean theorum and the equation of a line.

You will also want to memorize some permutation and combination formulas, ie how many combinations you can make with 8 beads, how many combinations you could make if you only chose 5 of those, etc.

Most importantly, though, you'll need to remember techniques.... like how to solve for variables, how to do long division, how to add/multiply/etc fractions....

There are so many topics on the GMAT I think the best thing is to go through your prep book and try to memorize the formulas, tables, and techniques. Make sure you understand any questions you get wrong, so next time you see a question of that type you will get it right.

Best wishes,

Tatiana

[dubc1982]

Great info, thanks a lot!

[dbaGMAT123]

Here is a website that I found with a lot of useful GMAT Formulas
Hope this helps!