Let a1,a2,a3,......,an be a set of numbers, average = (a1 + a2 + a3,+......+ an)/n
Fractions formulas:
Converting a mixed number to an improper fraction:
Converting an improper fraction to a mixed number:
Formula for a proportion:
In a proportion, the product of the extremes (ad) equal the product of the means(bc),
Thus, ad = bc
Percent:
Percent to fraction: x% = x/100
Percentage formula: Rate/100 = Percentage/base
Rate: The percent.
Base: The amount you are taking the percent of.
Percentage: The answer obtained by multiplying the base by the rate
Consumer math formulas:
Discount = list price × discount rate
Sale price = list price − discount
Discount rate = discount ÷ list price
Sales tax = price of item × tax rate
Interest = principal × rate of interest × time
Tips = cost of meals × tip rate
Commission = cost of service × commission rate
Geometry formulas:
Perimeter:
Perimeter of a square: s + s + s + s
s:length of one side
Perimeter of a rectangle: l + w + l + w
l: length
w: width
Perimeter of a triangle: a + b + c
a, b, and c: lengths of the 3 sides
Area:
Area of a square: s × s
s: length of one side
Area of a rectangle: l × w
l: length
w: width
Area of a triangle: (b × h)/2
b: length of base
h: length of height
Area of a trapezoid: (b1 + b2) × h/2
b1 and b2: parallel sides or the bases
h: length of height
volume:
Volume of a cube: s × s × s
s: length of one side
Volume of a box: l × w × h
l: length
w: width
h: height
Volume of a sphere: (4/3) × pi × r3
pi: 3.14
r: radius of sphere
Volume of a triangular prism: area of triangle × Height = (1/2 base × height) × Height
base: length of the base of the triangle
height: height of the triangle
Height: height of the triangular prism
Volume of a cylinder:pi × r2 × Height
pi: 3.14
r: radius of the circle of the base
Height: height of the cylinder