# Shared Flashcard Set

## Details

GMAT
Quant Formulas and Items to Memorize
83
11/01/2012

Term
 Prime Numbers between 0 and 20 (8)
Definition
 2,3,5,7,11,13,17,19
Term
 Prime Numbers between 21 and 40 (4)
Definition
 23,29,31,37
Term
 Prime Numbers between 41 and 60 (5)
Definition
 41,43,47,53,59
Term
 Prime Numbers between 61 and 80 (5)
Definition
 61,67,71,73,79
Term
 Prime Numbers between 81 and 100 (3)
Definition
 83,89,97
Term
 What is the mode?
Definition
 The list of numbers that appear most frequently.
Term
 This formula is used to determine the number of unordered subgroups of k items that can be selected from a group of n different items, where k < n
Definition
 The cominations formula,       [image]
Term
 This formula gives the number of ordered subgroups of r items that can be made from a set of n different items, where r < n
Definition
 The permutations formula,       [image]
Term
 Probability formula
Definition
 [image]
Term
 To find the probability that one or another of two mutually exclusive events occurs...
Definition
 add the probabilites of the two events.
Term
 To find the probability that one and another of two mutually exclusive events occur...
Definition
 multiply the probabilities of the two events.
Term
Definition
 x2 - y2 = (x+y)(x-y) (x+y)2 = (x+y)(x+y) = x2 + 2xy + y2 (x-y)2 = (x-y)(x-y) = x2 - 2xy + y2
Term
 Combined work formula, for more than two workers
Definition
 [image]   Where [image], [image] and [image] are the times taken by A, B and C respectively to complete the task alone and [image] is the time taken by them to complete the task when they are all working together.
Term
 Solving for quadratic equations   ex. x2 + x -6 = 0
Definition
 sum of the two numbers equals the middle constant, and the product of the two number equals the third contant.   (x+3)(x-2)
Term
 x/9 fractions
Definition
 Whatever the numerator is in the fraction, the outcome will be infinite of itself   ex. 2/9 = .22222 or 8/9 = .88888
Term
 x/8 fractions
Definition
 1/8 = .125, each then increase by .125
Term
 x/6 fractions
Definition
 1/6 = .16666, then each increase by .16666
Term
 x/7 fractions
Definition
 1/7 = .142, then each increase in the numerator increases by .142
Term
 What is a multiple?
Definition
 The product of a given integer and another integer.   ex. Multiples of 4 are, 4, 8, 12, 16,....
Term
 What is a factor?
Definition
 An integer that divides another integer without leaving a remainder.   ex. 3 is a factor of 12 because 3/12 = 4, without a remainder
Term
 Combined work formula, for two workers
Definition
 xy x+y
Term
 Simple interest formula
Definition
 Principal x (1+rt)   r=rate, t=time
Term
 Compound interest formula
Definition
 Principal x (1+r)t   r=rate, t=time
Term
 Overlapping sets formula, for only 2 groups
Definition
 total = group 1 + group 2 - both + neither
Term
 Order of operations
Definition
Term
Definition
 First, Outer, Inner, Last
Term
 Systems of linear equations rules
Definition
 to solve for all of the variables in a systems of equations, we must have at least as many distinct linear equations n as we have distinct variables n.   Two ways to solve: 1) substitution solve one equation for one fothe variables and substitute that variable into the other 2) combination add or subtract one equation from the other to cancel out one of the variables
Term
 Inequalities should be treated exactly as equations with two exceptions
Definition
 1) When we multiply or divide an inequality by a negative number, we must reverse the direction of the inequality sign   2) Single-variable equations are usually solved for a specific value, whereas inequalities can only be solved for a range of values
Term
 Rate formula
Definition
 d=rt
Term
 Average formula, for speed
Definition
 average speed = total distance                          total time
Term
 Side proportions of special right triangles to recognize
Definition
 3:4:5 and 5:12:13
Term
 Formula for the area of a triangle.
Definition
 1/2(base)(height)
Term
 Interior angles of a triangle always add up to?
Definition
 180º
Term
 What does the external angle of a triangle always add up to?
Definition
 The sum of the two non-corresponding internal angles.
Term
 What ratio is the side length of a 30-60-90 right triangle?
Definition
 x : x√3 : 2x
Term
 What ratio is the side length of a 45-45-90 right triangle?
Definition
 x : x : x√2
Term
 What is the hypotenuse?
Definition
 The longest side of a right sided triangle.
Term
 Sum of interior angles of a polygon
Definition
 (n-2)180º
Term
 trapezoid area formula
Definition
 1/2(sum of the bases)(height)
Term
 area of a circle
Definition
 π r2
Term
 Circumference of a circle
Definition
 2πr
Term
 Area of a sector of a circle
Definition
 Area = ½ × r2 × θ   r=radius θ = angle of sector
Term
 Lenght of an arc of a circle and sector of circle
Definition
 x/360 = arc/C = sector/A   X = angle measurement C = circumference A = area of circle
Term
 Slope formula
Definition
 m = rise = y1 - y2         run     x1 - x2
Term
 line formula
Definition
 y=mx+b   m = slope b = y-intercept
Term
 In coordinate geometry, when two lines are perpendicular their slopes are
Definition
 negative reciprocals   line with the slope -2 has a negative reciprocal of 1/2, and makes the line perpendicular
Term
 Strategies
Definition
 When picking numbers, avoid picking numbers that appear in the question stem.
Term
 Strategies
Definition
 When dealing with variables in exponents, find a common base.
Term
 Strategies
Definition
 When a Data Sufficiency question involves a number's absolute value, remember that the number itself may be negative.
Term
 Strategies
Definition
 Be comfortable with positive/negative rules forwards and backwards. A negative resulf of a product means you multiplied a positive and a negative.
Term
 Strategies
Definition
 Use the Least Common Denominator when picking numbers with fractions.
Term
 Strategies
Definition
 Picking numbers is a very powerful strategy when solving for odds and evens, divisibility, and similar number properties.
Term
 Strategies
Definition
 For "which of the following" questions, generally the answer choice is in the bottom, (D & E).
Term
 Strategies
Definition
Term
 Strategies
Definition
 Symbol problems are substitution problems in disguise.
Term
 Strategies
Definition
 Let the Data Sufficiency question's information tell you in what form to manipulate the statements.
Term
 Strategies
Definition
 Absolute values are always 0 or a positive number. They are never negative
Term
 Data Suffiency   Insufficient
Definition
 Half the time statements (A) and (B) are both insufficient.
Term
 Data Suffiency   Hard Questions
Definition
 Skip statements that you do not understand. Eliminate as much as possible.
Term
 First Data Sufficiency (DS) Questions
Definition
 Calculate out the first DS questions to make sure they are correct. It is important to start out the section strong.
Term
 Data Suffiency   Hard Questions
Definition
 On harder DS questions, answer choices tend to be more sufficient than they might appear. • DON’T CHOOSE (E) if you have to guess. • Pick between (A) or (C), if you can eliminate (B). • Historically, (A) is slightly more common as the right answer.
Term
 Data Suffiency Equations
Definition
 For a system with n variables: • If you have as many distinct linear equations as you have variables, you can answer ANY question about the system. • If you are only asked to solve for part of the system, you don’t necessarily need all n equations. • If you are asked to solve for a relationship instead of the value of variables, you don’t necessarily need all n equations.
Term
 What is a Verb?
Definition
 A verb or compound verb asserts something about the subject of the sentence and express actions, events, or states of being.
Term
 What is a Noun?
Definition
 A noun is a word used to name a person, animal, place, thing, and abstract idea.
Term
 What is a pronoun?
Definition
 A pronoun can replace a noun or another pronoun. You use pronouns like "he," "which," "none," and "you" to make your sentences less cumbersome and less repetitive.
Term
 Finding the Subject of a sentence.
Definition
 A someone must be a person and a something must be a thing, place, or idea. So guess what? The subject is usually a noun because a noun is a person, place, thing, or idea. Although, sometimes the subject is a pronoun such as he, they, it, and so forth.   One way to think about the subject is to say that the subject is the who or what part of the subject-verb pair. The subject-verb pair is the main idea of the sentence, stripped to essentials
Term
 Sentence Correction Present Perfect verb tense
Definition
 "have" or "has" followed by past tense verb describes an action that began in the past but continues into the present
Term
 Sentence Correction past perfect
Definition
 "had" followed by a verb in the past tense used when there are two actions in the sentence, describes an action that stared in the past and ended in the past
Term
 Sentence Correction Modifiers
Definition
 part of a sentence that provides more information about a person or thing in the sentence should be as close as possible to the noun it is modifying
Term
 Sentence Corrections Challenging Pronouns
Definition
 "that" is restrictive; what follows is necessary to the subject of the clause.Ex. The car that is parked next to the fire hydrant, will be ticketed. "which" is non-restrictive; using which determines the information that follows is irrelevant to the suject of the clause. Ex. The car which is red, will be ticketed.
Term
 Sentence Correction Parallel Structure
Definition
 A sentence maintains parallel structure when its components maintain consistent grammatical structure. Generally tested with a list or a 2-part idiom.
Term
 Sentence Correction Passive voice
Definition
 Passive voice: The cake was bought by Alison. Active voice: Allison bought the cake.
Term
 Sentence Correction Redundancy
Definition
 A sentence is redundant when a word or phrase in a sentence unnecessarily repeats meaning.
Term
 Sentence Correction Wordiness
Definition
 Wordiness errors arise when meaning is conveyed in a roundabout manner, meaning may not be duplicated, but its not conveyed in the most efficient way possible
Term
 Sentence Correction Idioms
Definition
 as...as between...and regard...as
Term
 Sentence Correction Misused words: less/fewer
Definition
 Use less to talk about things we cant count Use fewer to talk about things we can count
Term
 Sentence Correction Misused words: number/amount
Definition
 Use number to talk about things we can count Use amount to talk about things we cant count
Term
 Sentence Correction Misused words: between/among
Definition
 Use between when only two options are available Use among when more than two options are available
Term
 Sentence Correction Misused words: whether/if
Definition
 Whether is correct when we're discussing two options If is correct for more than two options.
Term
 Sentence Correction Comparisons
Definition
 Comparisons in sentences need to be like terms, people compared to people.   Common indicators of comparisons: like, unlike, similar to, as, so, in contrast to
Term
 Odd and Even
Definition
 Odd + Odd = Even          Odd x Odd = Odd Even + Even = Even      Even x Even = Even Odd + Even = Odd        Odd x Even = Even   And mulitplication involving an even # creates and even product
Term
 √2
Definition
 1.41
Term
 √3
Definition
 1.73
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