GRE Math Formulas and Strategies (68 Cards)
by Nina
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1 A radius extending to the tangent line of a circle perpendicular
2 A triangle formed by connecting the endpoints of t isosceles; right
3 Approximately what percentage of the normal distri 34%*2=68%
4 a^2+b^2>c^2 if a triangle is... acute
5 a^2+b^2<c^2 if a triangle is... obtuse
6 cos(30) sqrt(3)/2
7 cos(45) sqrt(2)/2
8 cos(60) 1/2
9 Counting from n to m, what is the total if both en m-n+1
10 Counting from n to m, what is the total if neither m-n-1
11 Counting from n to m, what is the total if only on m-n
12 days would the water supply last for 9 people? The resulting equation is inversely proportional (not proportional, like a baking recipe). So, set up a proportional equation and then flip one of the sides. It is important to use the same units on each side! 15/9 = 21/x -> 15/9 = x/21 -> x=35.
13 Distance (rate)(time) d=rt
14 For a rectangle of dimensions l*w surrounded by a (l+2s)(w+2s)
15 For an inequality -y<0<x-y<0<1-y, how For this type of problem, since you can
16 Formula for distance problems distance=rate×time or d=rt
17 How can you find the units digit of 2*3^27, or 7^4 On these types of problems, the units digit repeats every few powers. Write out them until it repeats, then extrapolate by counting from a multiple of the repeat interval.
18 How can you tell if a number is divisible by 12? Its digits add to a multiple of 3 and the last two digits are divisible by 4.
19 How can you tell if a number is divisible by 3? Its digits add to a multiple of 3.
20 How can you tell if a number is divisible by 4? The last two digits are divisible by 4.
21 How can you tell if a number is divisible by 6? It is even and its digits add to a multiple of 3.
22 How can you tell if a number is divisible by 8? The last three digits are divisible by 8.
23 How can you tell if a number is divisible by 9? Its digits add to a multiple of 9.
24 How can you tell where the median of a graph is? It divides the area in half.
25 How do the 25th percentile and the average of the The 15th percentile is greater than the average of the 10th and 40th because the tail points in the negative direction.
26 How do the 75th percentile and the average of the The 75th percentile is less than the average of the 60th and 90th because the tail points in the positive direction.
27 How many integers with all even digits are there b 2*5*5=50 (disguised permutation question)
28 How would you find the number of multiples of x be Find M/x rounded down, then subtract the number of multiples between 1 and N.
29 If two parallel lines are cut by a transversal, wh The acute angles are equal and the obtuse angles are equal.
30 In multiples of x, what are the lengths of the leg x, x*sqrt(3), 2x
31 Or are they equal, or is there not enough informat (a+b)^2 is greater.
32 Rate d/t (distance)/(time)
33 sin(30) 1/2
34 sin(45) sqrt(2)/2
35 sin(60) sqrt(3)/2
36 tan(30) sqrt(3)/3
37 tan(45) 1
38 tan(60) sqrt(3)
39 The formula for arc length of a circle is (x/360)*2*pi*r
40 The formula for sector area of a circle is (x/360*pi*r^2
41 The largest angle of a triangle is opposite the __ shortest, longest
42 The sum of all angles around a point 360°
43 The two triangles formed by a diagonal cutting acr congruent
44 Time (distance)/(rate) d/r
45 What are the relationships between the angles form The angles on opposite sides of the X intersection are equal (and supplementary on the same side).
46 What are the relationships between the sides and a 1) Opposite sides and opposite angles are equal.
47 What does it mean for a graph to be left-skewed or The "tail" of low-frequency values points in the negative direction, and toward the hill is positive. The mean is less than the median.
48 What does it mean for a graph to be right-skewed o The "tail" of low-frequency values points in the positive direction, and toward the hill is negative. The mean is more than the median.
49 What is the difference relationship between sides The difference of any two sides is less than the third side.
50 What is the formula for a mixture of 2 components (m+c_A)*f_O=c_O
51 What is the formula for compound interest? V=P(1+r/n)^(n*t) with r in fraction form
52 What is the formula for each exterior angle of a p 360/n
53 What is the formula for each interior angle of a p ((n-2)*180)/n
54 What is the formula for simple interest? V=P+r*t
55 What is the formula for the area of a parallelogra A=b*h, where b is the length of the horizontal sides and h is the length of a vertical line inside the parallelogram extending from a vertex.
56 What is the formula for the area of a trapezoid? (1/2)*(b1+b2)*h
57 What is the formula for the area of an equilateral s^2*sqrt(3)/4
58 What is the formula for the length of a diagonal a sqrt(l^2+w^2+h^2)
59 What is the formula for the number of diagonals of n(n-3)/2
60 What is the formula for the number of possible com n!/(r!*(n-r)!)
61 What is the formula for the radius of the circle t (r1+r2)/2
62 What is the length of the first leg of a _-12-13 t 5
63 What is the length of the second leg of a 3-_-5 tr 4
64 What is the number of possible permutations for n n!/(n-r)!
65 What is the sum relationship between sides of a tr The sum of any two sides is greater than the third side.
66 What is the triangle inequality? |a+b|<=|a|+|b|
67 Without using a calculator, how do you find the nu Factor out 1/10^|m-n|, since x^n*y^n=(x*y)^n. 0.5^n-m or 0.2^m-n may now be calculated on the calculator. Alternatively, for the latter case, now factor out (1/10)^m-n and just calculate 2^m-n.
68 You have a set of 10 books consisting of four of t Break the problem down into P1, P2, and P3.