Edexcel A Level Maths - Statistics
Linear Regression - ANSWER y = axⁿ
logy = loga + nlogx
Exponential Regression - ANSWER y = ab^x
logy = loga + xlogb
Normal Approximation - ANSWER µ = np
σ =√(np(1-p))
Mean - ANSWER ∑x ÷ n
GF: ∑xf ÷ ∑f
Variance - ANSWER (∑x²/n) - (∑x/n)²
Standard Deviation - ANSWER √variance
Histograms: Height - ANSWER Area = k x frequency
,Frequency Density - ANSWER frequency ÷ class width
Population - ANSWER Whole set of items of interest.
Census - ANSWER Observes/measures every member of a population
Sample - ANSWER Selection of observations taken from a subset of the population which is
used to find out info about the population.
Sampling Frame - ANSWER A list of individuals (named or numbered) from whom the
sample is drawn
Random Sampling - ANSWER Every member of the population has an equal chance of being
selected
Systematic Sampling - ANSWER Every nth person is chosen.
Stratified Sampling - ANSWER Population is divided into mutually exclusive Strat and a
random sample is taken from each.
Quota Sampling - ANSWER Interviewer selects a sample that reflects the characteristics of
the population
Opportunity Sampling - ANSWER Choosing whoever is available
Continuous Variable - ANSWER Can take any value in a given range
,Discrete Variable - ANSWER Takes specific values in a given range
Conditions for Binomial - ANSWER Fixed no. of trials
2 possible outcomes
Outcomes are independent
Fixed probability of success
Probability: Independent if... - ANSWER P(A∩B) = P(A) X P(B)
P(A|B) = P(A)
Probability: Mutually exclusive if... - ANSWER P(A∩B) = 0
P(A∪B) = P(A) + P(B)
Conditional Probability - ANSWER P(A|B) = P(A∩B)/P(B)
Probability Addition Rule - ANSWER P(A∪B) = P(A) + P(B) - P(A∩B)
If there are 3 events, and A and B are mutually exclusive... - ANSWER P(A∪B∪C) = P(A) +
P(B) + P(C) - P(A∩C) - P(B∩C)
What is a DRV - discrete random variable - ANSWER it is a random variable that can only
take certain values
... - ANSWER ...
, probability mass function - ANSWER a function that gives the probability that a discrete
random variable is exactly equal to some value
what does a probability distribution do - ANSWER describes the probability of any outcome
in the sample space
P(A/B) = - ANSWER (P(A n B))
---------------
P(B)
If they are independent events P(A) * P(B) = - ANSWER P(A N B)
SUM OF P(X=x) = - ANSWER 1
formula for probability X=r where X is the number of desired outcomes
binomial distribution formula - ANSWER nCr P^r * (1-p)^(n-r)
p = probability of success
r = number of times you want success
n= number of trials
standard deviation - ANSWER a computed measure of how much scores vary around the
mean score
general probability addition rule - ANSWER P(A∪B)=P(A)+P(B)−P(A∩B)
Linear Regression - ANSWER y = axⁿ
logy = loga + nlogx
Exponential Regression - ANSWER y = ab^x
logy = loga + xlogb
Normal Approximation - ANSWER µ = np
σ =√(np(1-p))
Mean - ANSWER ∑x ÷ n
GF: ∑xf ÷ ∑f
Variance - ANSWER (∑x²/n) - (∑x/n)²
Standard Deviation - ANSWER √variance
Histograms: Height - ANSWER Area = k x frequency
,Frequency Density - ANSWER frequency ÷ class width
Population - ANSWER Whole set of items of interest.
Census - ANSWER Observes/measures every member of a population
Sample - ANSWER Selection of observations taken from a subset of the population which is
used to find out info about the population.
Sampling Frame - ANSWER A list of individuals (named or numbered) from whom the
sample is drawn
Random Sampling - ANSWER Every member of the population has an equal chance of being
selected
Systematic Sampling - ANSWER Every nth person is chosen.
Stratified Sampling - ANSWER Population is divided into mutually exclusive Strat and a
random sample is taken from each.
Quota Sampling - ANSWER Interviewer selects a sample that reflects the characteristics of
the population
Opportunity Sampling - ANSWER Choosing whoever is available
Continuous Variable - ANSWER Can take any value in a given range
,Discrete Variable - ANSWER Takes specific values in a given range
Conditions for Binomial - ANSWER Fixed no. of trials
2 possible outcomes
Outcomes are independent
Fixed probability of success
Probability: Independent if... - ANSWER P(A∩B) = P(A) X P(B)
P(A|B) = P(A)
Probability: Mutually exclusive if... - ANSWER P(A∩B) = 0
P(A∪B) = P(A) + P(B)
Conditional Probability - ANSWER P(A|B) = P(A∩B)/P(B)
Probability Addition Rule - ANSWER P(A∪B) = P(A) + P(B) - P(A∩B)
If there are 3 events, and A and B are mutually exclusive... - ANSWER P(A∪B∪C) = P(A) +
P(B) + P(C) - P(A∩C) - P(B∩C)
What is a DRV - discrete random variable - ANSWER it is a random variable that can only
take certain values
... - ANSWER ...
, probability mass function - ANSWER a function that gives the probability that a discrete
random variable is exactly equal to some value
what does a probability distribution do - ANSWER describes the probability of any outcome
in the sample space
P(A/B) = - ANSWER (P(A n B))
---------------
P(B)
If they are independent events P(A) * P(B) = - ANSWER P(A N B)
SUM OF P(X=x) = - ANSWER 1
formula for probability X=r where X is the number of desired outcomes
binomial distribution formula - ANSWER nCr P^r * (1-p)^(n-r)
p = probability of success
r = number of times you want success
n= number of trials
standard deviation - ANSWER a computed measure of how much scores vary around the
mean score
general probability addition rule - ANSWER P(A∪B)=P(A)+P(B)−P(A∩B)
