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Win Gre Math > Math Stuff > Flashcards

Math Stuff Flashcards

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1
Q

Simple interest

A

V=P(1+rt/100)

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2
Q

Compound interest

A

V=P(1+r/(100n))^(nt)

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3
Q

Summation

A

Sum(x,i=1,n)=n(n+1)/2
Sum(x,i=a,b)=(b-a+1)(b+a)/2
Sum(S[i],i=a,b)=(b-a+1)(S[b]+S[a])/2
S is sequence of evenly spaced number form similar to S[i]=c+k(i-1), c is initial number S[1] and k and the spacing number, ex 1, 3, 5 c is 1 and k is 2
equation also works for when start at 0 or negative

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4
Q

Factor

A

1 and itself and also negative

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5
Q

Prime number

A

Not 1

2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47

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6
Q

Odd even

A 
e+-o=o
e+-e=e
o+-o=e
e×e=e
e×o=e
o×o=o
o/o=o
e/e=e||o
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7
Q

Least common multiple

A

30,75=150
2,3,5;3,5,5=2,3,5,5
Union of prime factor

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8
Q

Greatest common divisor (factor)

A

30,75=15
2,3,5;3,5,5=3,5
Intersect of prime factor

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9
Q

Power of 2

A 
0   1
1   2
2   4
3   8
4   16
5   32
6   64
7   128
8   256
9   512
10 1024
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10
Q

Polynomial terms

A 
4xy^2+5
Term=2
Coefficient=4
Constant=5
Degree=1+2=3
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11
Q

Perpendicular slope

A

a/b -> -b/a

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12
Q

Graph symmetry

A

X axis: a,b -> a,-b
Y axis: a,b -> -a,b
Origin: a,b -> -a,-b
Line of symmetry y=x: a,b -> b,a

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13
Q

Reciprocal

A

a/b -> b/a

a -> 1/a

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14
Q

Circle graph

A

(x-a)^2+(y-b)^2=r^2
Center a,b
Radius r

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15
Q

Congruent line segment

A

Line segment with equal length

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16
Q

Angles name

A

Vertical angle = opposite angle = angle on opposite side of intersection
Congruent angle = angle with equal measure

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17
Q

Polygon, regular angle and interior angle

A 
Interior angle = 180*(#sides-2)
Pentagon = 5, 108, 540
Hexagon = 6, 120, 720
Heptagon = 7, 128.57, 900
Octagon = 8, 135, 1080
Nonagon = 9, 140, 1260
Decagon = 10, 144, 1440
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18
Q

Triangle name

A 
Equilateral = 3 congruent side, 60 degree
Isosceles = 2 congruent side, 2 same angle
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19
Q

Common right triangle

A 
45, 45, 90 = 1, 1, root(2)
30, 60, 90 = 1, root(3), 2
60, 60, 60 = 1, 1, 1
3, 4, 5
5, 12, 13
8, 15, 17
7, 24 ,25
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20
Q

Congruent polygon ex triangle

Similar polygon ex triangle

A

Can match same length and angle

Same shape or angle but different size

21
Q

Trapezoid area

A

(1/2)(base1+base2)height

22
Q

Chord

A

Any line joining 2 points in circle

23
Q

Central angle
Measure of arc
Sector

A

Angle with vertex at center of circle
Measure if central angle
Regious boud by arc and 2 radii (radius)

24
Q

Inscribe

Circumscribe

A

All vertices lie on container
Contain all vertices in its parameter, or side tangent to circle
If one side of triangle inscribe in circle is diameter, it is right triangle

25
Q

Cylinder

A

2 basrs and lateral surface
Volume = pi r^2 h
Area = 2pi r^2+2pi r h

26
Q

Sector

A

Part of circle graph

27
Q

Quartile

A

Start at median and half the top and bottom half

2 4 4 5 7 7 7 7 7 7 7 8 9 9 9 9
2 4 4 5 Q1 7 7 7 7 Q2 7 7 7 8 Q3 9 9 9 9
Q1 = (5 + 7)/2
Q2 = median = 74 in quartile 1
Q3 = (8+9)/2 = 8.5

2 4 4 [5] 7 7 7 [7] 7 7 7 [8] 9 9 9
Q1 = 5
Q2 = 7
Q3 = 8

28
Q

Range

Interquartile range

A

Biggest - smallest

Q3 - Q1

29
Q

Standard deviation or population standard deviation

Sample standard deviation

A

Sqrt(sum((x-avg)^2)/count)

Sqrt(sum((x-avg)^2)/(count-1))

30
Q

Standardization

A

For each ((x-avg)/std)
Same as finding how many standard deviation away from average
Ex avg 32.5, std 7.1
48 is (48-32.5)/7.1 = 2.2 standard value or 2.2 std away from avg

31
Q

Mutually exclusive, disjoint

A 
No element in common
Event cannot occur at same time
|A∩B| = 0
|A∪B| = |A| + |B|
P(A and B) = 0
P(A or B) = P(A) + P(B)
32
Q

A∩B
A∪B
P(A and B)
P(A or B)

A

Intersect
Union
|A∪B| = |A| + |B| - |A∩B|
P(A or B) = P(A) + P(B) - P(A and B)

33
Q

Combination

Permutation

A

C(n,k)=n!/((n-k)!k!)

P(n,k)=n!/(n-k)!

34
Q

Sample space

Event

A

All possible set of outcomes

Particular set of outcome

35
Q

Independent

A

Occurrence of one does not affect the other
P(A and B) = P(A)P(B) != 0
Can’t be both mutually exclusive and independent

36
Q

Mean of random variable

expected value

A

Average of distribution

37
Q

Uniform distribution

A

probability distributed uniformly over all possible outcome

All outcome equally likely

38
Q

Normal distribution

A 
Mean, median, mode nearly equal
Fairly symmetrical about mean
About 2/3 data (0.68) within 1 std
Almost all data (0.96) within 2 std
2% 14% 34% 34% 14% 2%
0.1% 2.1% 13.6% 34.1% 34.1% 13.6% 2.1% 0.1%
39
Q

Normal distribution shape

A

Less std, less spread, narrower and taller graph, data more concentrated
Different center, different mean

40
Q

Area under probability graph

A

Equals 1

Sum of all probabilities = 1

41
Q

Standard normal distribution

A

Normal distribution mean 0, std 1

Do standardization, for each subtract mean and divide std

42
Q

Percentage wording

A

x is what percent more than y : 100(x-y)/y
x is what percent less than y : 100(y-x)/y
what is percent increase from y to x : 100(x-y)/y
what is percent decrease from y to x : 100(y-x)/y
x is what percent of y : 100(x/y)

43
Q

Evenly spaced set

A

average equals median\

ex set of S[n] = k*n+c

44
Q

Percentile

A

Portion of a group that score below some number

ex. 50 is 32 percentile means 32% less than 50 and 68% more than or equal to 50

45
Q

Combination with repetition

A

(total # item)!/((group 1)!(group 2)!…)
ex # ways rearrange MISSISSIPPI -> 1 M, 4 I, 4 S, 2 P ->
11!/(1!4!4!*2!)

46
Q

Central and inscribed angle

A

Central angle’s vertex is center of circle.
Inscribed angle’s vertex is on circle’s parameter.
If central and inscribed angle share same arc, inscribed angle is half the central angle.
The inscribed angle has angle x, inscribed in a circle is half of the central angle (2x) that produce the same arc on the circle.
Angle is 90 only if one of the side is diameter.

47
Q

x as many A as B

A

A = xB

48
Q

remainder

A

x/y remainder z

y > z

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