Ucas Exam - Stats And Mechanics Flashcards
Standard deviation (words)
The root of: the mean of the squares minus the square of the means
Standard deviation formula
√(Σfx^2/Σf)-(Σfx/Σf)^2
Linear interpolation formula
LB+(PL/GF x CW)
Coded data
y = (x-a)/b
Mean of coded data
ȳ = (x̄-a)/b
Standard deviation of coded data
σy = σx/b
Where to draw cross on cumulative frequency graph
Upper end point of the class width
Where to draw cross for frequency polygon
Midpoint of class width
Frequency formula
Frequency = frequency density x class width
What formula is for mutually exclusive probability events
P(A U B) = P(A)+P(B)
What formula is for statistically independent probability events
P(A n B) = P(A) x P(B)
What is the addition formula for P(A U B)
P(A) + P(B) - P(A n B)
What is the multiplication formula for P(B|A)
P(B n A)/ P(A)
Binomial PD without calc
nCr x P(failure)^no.failures x P(success)^no.success
Binomial distribution, what does each letter mean
X ~ B(n,r)
n = number of trials
p = probability of success
Binomial PD
P(X=y)
Binomial CD
P(X ≤ y)
Normal distribution p(1 sd from mean)
68%
Normal distribution p(2 sd from mean)
95%
Normal distribution p(3 sd from mean)
99.7%
Expression for normal distribution and what does each letter mean
X ~ N(μ, σ^2)
Mu = mean
σ = standard deviation
What is the probability in Inverse normal
The area to the left
What is the standard normal distribution
Z ~ N(0,1^2)
What is the formula for z in standard normal
Z = (X - μ)/σ