S1 Flashcards
Mean of discrete data
Sum of x/ n
Mean of grouped data
Sum of fx / sum of f
Combined mean equation
(N1mean1+n2mean2)/n1+n2
Discrete variance equation
Sum of x squared /n - (sum of x/n) squared
What is an outlier?
> upper quartile + 1.5 x interquartile range
< lower quartile -1.5 x interquartile range
What should you look for when comparing data?
Measure of location and measure of spread
How do you work out frequency from a histogram?
Area underneath
Equation for frequency density
frequency/class width
How can you determine whether or not a distribution is skewed?
Quartiles
Box plots
Measures of location
Calculate 3(mean - median)/ standard deviation
How can you use measure of location to determine skewness?
Mode = median = mean (symmetrical)
Mode < median < mean ( positive)
Mode > median > mean (negative)
What is a sample space?
The set of all possible outcomes of an experiment
what is an event?
A collection of one or more outcomes.
What is the equation for P(AuB)?
A+b-i
What sort of data is represented on a histogram?
Continuous and summarised in a group frequency distribution
What must a random variable always be?
A numerical value
How does a RANDOM variable occur?
when the value of a variable is the outcome of an experiment
