Pre-Algebra / Misc Math / Statistics Flashcards
DDX
Denominator X Denominator, Cross Multiply
operations on dissimilar fractions (+/-)
of
changing questions to equations
x
multiply
is
changing questions to equations
=
what
changing questions to equations
N
unknown
arithmetic sequence formula
to get nth term of sequence
an = a1 + (n-1)d
a1 = first term
n = number of terms
d = common difference
arithmetic sequence shortcut
number of terms
(last term - first term) / common difference
+ 1
arithmetic sequence shortcut
average of all terms
(last term + first term) / 2
arithmetic sequence shortcut
sum of all terms
(last term + first term) / 2
x number of terms
average x number of terms
calculating page numbers
inclusive of pages
last page - first page + 1
calculating page numbers
exclusive of pages
last page - first page - 1
how to get root of decimal
- drop decimal points
- perform root operation
- divide decimal places of orig by index of root to get dp of final answer
- move decimal point accordingly
DOST
Distance Over Speed / Time
used for distance problems
Percent Something
something / original
x 100
used to get the percent of a number from the original
same as PERCENT INCREASE
- increase / orig x 100
JUTSU
Jepjep’s Ultimate Technique, Super Ultimate
- repeating or non-repeating
- order important or not
used in permutation and combination questions
order important: SAD (sequences/seats, arrangements, digits)
order Not important: GC (group, choose/select)
JUTSU
combination formula
Jepjep’s Ultimate Technique, Super Ultimate
answer in R/NR /
blank!
blank! = number of blanks factorial
trends on fractions
same denominator
higher numerator
higher fraction value
directly proportional
trends on fractions
same numerator
higher denominator
lower fraction value
indirectly proportional
Compound Interest Formula
A(t) = P(1+r/n)^nt
P : principal
r : rate of interest (convert % to decimal)
n : compounding process (annual, monthly, etc.)
t : time
UTOT Techinque
Simple Interest Formula
I = Prt
P : principal
r : rate of interest (convert % to decimal)
t : time
A ∪ B
a union b
Sets Theory
A+B - A∩B
union : or
ornion
A ∩ B
a intersection b
Sets Theory
A+B - A∪B
intersection: and
andtersection
Golden Average Rule
don’t average the average
final ave = total sum / total n
total sum = average x n
Average Speed
don’t average the average
speed is average
ave. speed = total distance / total time
pigeonhole principle
worst case scenario + 1
can be used in minimum number of students or minimum number of draws
geometric sequence
sequence with common ratio
a number is multiplied or divided to each term to get the next one
percentile, docile, and quartile formula
percentile : divides data set into 100 parts
docile : divides data set into 10 parts
quartile : divides data set into 4 parts
L = j/k
x N
L : observation at certain location
j : location under percentil/docile/quartile
k : division of data set
N : population or sample size
mean
measure of central tendency
average
median
measure of central tendency
middle value when data set is arranged from lowest to highest
mode
measure of central tendency
most common value
number that appeared the most times
probability formula
P = number of desired / total outcomes
