Formulas Flashcards
No of factors of a no expressed as 2ᵃ.3ᵇ.5ᶜ.7ᵈ… (a, b, c, d… >= 1)
Total=> (a+1)(b+1)(c+1)(d+1)…; Odd=> (b+1)(c+1)(d+1)…; Even=> total - odd
(n+1)²
n² + n + (n+1)
Work Questions
A=RT; combined work rate of people/machines working together = SUM of individual work rates
Set of items with identical items [No of distinct arrangements]
n! / (b! c! d!)
Average velocity
Total distance / Total time
Relationship: LCM & HCF of M & N
LCM x HCF = M x N
Simple interest
Principal x Rate x Time
nth term of a sequence
aₙ = a₁ + (n-1)d
Slope b/w 2 points
rise/run (y₂-y₁ / x₂-x₁)
% change
[(New - Orig)/Orig] x 100
Range
Max - Min
Equation of a Line (given slope & 1 point)
y-y₁ = m (x-x₁)
Factor of every number
1
Distance b/w 2 points
rootof [ (y₂-y₁)² + (x₂-x₁)² ]
% (part, whole)
(part/whole) x 100
Parabola (vertex)
y=ax²+bx+c; x = -b/2a
Average of whole (A1 - p1, A2 - p2, A3 - p3)
A1p1+A2p2+A3p3
Sum of integers b/w two numbers
no of integers / 2 [first no + last no]; number of integers x to y inclusive = y-x+1
Compound interest (total amount)
p(1+r/n)^nt
Binomial Formula
nCr * p^r [ (1-p)^(n-r) ]
P(atleast 1 occurence of A)
1 - P(No occurence of A)
Sum of all factors of a prime no (X)
1 + X
General Events - P(A and B)
P(A)P(B/A) (or) P(B)P(A/B)
General Events - P(A or B)
P(A) + P(B) - P(A and B)
Independent Events - P(A and B)
P(A) x P(B)
Independent Events - P(A or B)
P(A) + P(B) - [ P(A) x P(B) ]
Mutually Exclusive Events - P(A and B)
0
Mutually Exclusive Events - P(A or B)
P(A) + P(B)
Order doesn’t matter & repetition is allowed
(r + n - 1)! / r! (n - 1)!
Order doesn’t matter & repetition is NOT allowed
n! / r! (n - r)!
Order matters & repetition is allowed
n^r
Order matters & repetition is NOT allowed
n! / (n - r)!
X/Y=?
Q+(R/Y)
X/Y=?
Q+(R/Y)
