Statistics Y10 Probability Distributions Flashcards
(22 cards)
what is a binomial distribution
a set of possible outcomes where all outcomes are independent and discrete, have the same probability of success and have a fixed number of trials
representation for binomial distribution
B(n, p)
B = binomial distribution
n = number of trials
p = probability of success
calculate mean of binomial distribution
number of trials * probability of success
what is n choose r (nCr)
number of ways of choosing r items from n choices
conditions for normal distribution
- continuous data
- symmetrical data
- mode/median/mean are all the same
- (large data set)
how much of the date is within 1 standard deviation of the mean
68%
how much of the date is within 2 standard deviations of the mean
95%
how much of the date is within 3 standard deviations of the mean
99.8%
calculate variance
standard deviation^2
what is variance
a measure of how spread out the data is
representation for normal distribution
N(μ, σ^2)
N = normal distribution
μ = mean
σ^2 = variation
what does a smaller variance mean
- more concentrated data
- higher peak on a graph
what does a larger variance mean
- less concentrated data
- lower peak on a graph
what is the standardised score
the number of standard deviations away from the mean
what are standardised scores used for
comparing two sets of data if both are normally distributed
calculate standardised score
(score - mean) / standard deviation
what does quality assurance involve
- collecting samples
- comparing with desired standards
- taking actions if limits not met
where should the warning limit and action limit be
about 2 and 3 standard deviations away from the mean respectively
what happens if the data is between the warning limits
data is acceptable
what happens if the data is between the warning limit and action limit
take another sample
what happens if the data is outside the action limit
take action (stop production)
what is a control chart in comparison to a quality assurance chart
the same but asymmetrical
