Quant Flashcards
Primes
2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37
% change formula
(change amount/original amount)*100
Slope
Rise/Run –> (y2-y1)/(x2-x1)
Special Products: Difference of Squares
x^2-y^2 –> (x+y) (x-y)
Special Products: (x+y)^2
x^2+2xy+y^2
Special Products: (x-y)^2
x^2-2xy+y^2
Area of a Triangle
area = 1/2 base*height
Angles in a Triangle
All angles sum to 180* –> x+y+z=180
Similar Triangles
Similar Triangles have all the same angles and sides that are proportionate (a:c equals d:f)
The Side Rule
The third side of a triangle is greater than the difference of the other two sides and less than their sum (a+b) > c > (b-a)
Area of a rectangle
length * width
Area of a square
side^2
Area of a parallelogram
base * height
Sum of angles in a polygon
sum of angles in a polygon = 180(n-2) –> (n = number of sides)
volume of a box
volume = lwh
surface area of a box
2lw + 2wh + 2lh
volume of a cylinder
volume = ∏r^2h
Surface area of a cylinder
Surface area = 2∏r^2 + 2∏rh
Central angle
A central angle has a vertex that lies at the center point of the circle. An inscribed angle has its vertex on the circle itself rather than on the center of the circle. An inscribed angle is equal to half of the arc it intercepts
Diameter of a circle
2r - if one of the sides of an inscribed triangle is a diameter of the circle, then the triangle must be a right angle.
Area of a circle
Area = ∏r^2
Circumference
∏d OR 2∏r
Pythagorean Theorem
In a right triangle, a^2 + b^2 = c^2 –> where a and b are the legs (shorter sides) and c is the hypotenuse
Pythagorean Triples
The most common are: 3-4-5, 5-12-13, 7-24-25, and 8-15-17
Angle/side relationship
Side length corresponds with angle size.
Special Right Triangles
30-60-90 and 45-45-90
Isosceles Triangle
Two sides are the same length
Equilateral Triangle
All sides are the same length and all angles are 60*
Sector
Sector area and arc length are proportional to angle size. Here, the angle is 60. Since there are 360 in a circle, the sector (grey area) takes up 1/6 of the circle. Thus, its area is 1/6 of the total area, and its arc length is 1/6 of the circumference.
Lines and Angles Equation
All angles in a line add to 180* –> x+y = 180
Parallel Lines
When a line intersects with two parallel angles, the resulting intersections are identical
Intersecting Lines
When two lines intersect, opposite angles are equal
Distance Formula
√(x2-x1)^2 + (y2-y1)^2
Line Equation on a graph
y=mx+b –> m=slope, b=y-intercept
Midpoint Formula
((x1+x2)/2, (y1+y2)/2)
Find Degrees of Polygons (i.e hexagon)
(n-2) * 180
Find the degree of a single angle of a polygon (i.e hexagon)
(n-2) * 180/n
Evenly Spaced List Formulas
Mean = median
Mean OR Median = (first + last)/2)
# of #’s for consecutive integers = (last - first/1) + 1
# of #’s for odd integers = (last - first/2) + 1
Sum = (# of #’s) * mean
Percent/Fraction/Decimal Conversions: 1%
1/100 - .01
Percent/Fraction/Decimal Conversions: 5%
1/20 - .05
Percent/Fraction/Decimal Conversions: 12.5%
1/8 - .125
Percent/Fraction/Decimal Conversions: 25%
1/4 - .25
Percent/Fraction/Decimal Conversions: 33.33%
1/3 - .33333
Percent/Fraction/Decimal Conversions: 37.5%
3/8 - .375
Percent/Fraction/Decimal Conversions: 40%
2/5 - .4
Percent/Fraction/Decimal Conversions: 50%
1/2 - .5
Percent/Fraction/Decimal Conversions: 60%
3/5 - .6
Percent/Fraction/Decimal Conversions: 80%
4/5 - .8
Percent/Fraction/Decimal Conversions: 87.5%
7/8 - .875
Percent/Fraction/Decimal Conversions: 90%
9/10 - .9
When I see comparison (>0, <0)
I know I’m dealing with positives and negatives
When I see x^2
I know the result is positive OR 0 but x itself can be positive, negative or 0
When I see x & y do not intersect
I know Line x & y are parallel
When I see x only has one factor, m, such that 1<m<x
I know integer x is prime
When I see x^4-9 OR x^2-1
I know this is a special product (difference of squares: x^2-y^2 = (x+y)(x-y)
When I see (-1)^2x vs. (-1)^2x+1
I know 2x is even and 2x+1 is odd, therefore the first quantity is positive and the second is negative → true for all values of x
What percentage falls between 1 standard deviation in both directions of a normal distribution?
68%
What percentage falls between 2 standard deviations in both directions of a normal distribution?
95%