Statistics · Second Year
Statistics
Second Year · Averages & range · Tap NEXT to begin
Section 1 of 2
The Three Averages
Mean, median, mode
Mean $=\dfrac{\text{sum}}{\text{how many}}$. Median = middle (order first). Mode = most common.
Worked example — mean of a list
Find the mean of $4, 7, 10, 3, 6$.
$\dfrac{4+7+10+3+6}{5} = \dfrac{30}{5}$
mean $= 6$
Now you try
You try
Find the median and mode of $3, 5, 5, 8, 9$.
Pen and paper out — try it before you reveal.
Already in order; middle value is the $3$rd
Mode = most common = $5$
median $= 5$, mode $= 5$
median $= 5$, mode $= 5$
Section 2 of 2
The Range
You try
Find the range of $12, 5, 18, 9$.
Pen and paper out — try it before you reveal.
Range = highest $-$ lowest $= 18 - 5$
range $= 13$
range $= 13$
Data types
Worked example — classify the data
Data can be numerical (discrete/continuous) or categorical (nominal/ordinal).
Numerical = numbers: discrete (counts) or continuous (a range)
Categorical = groups: nominal (no order) or ordinal (order)
the four types of data
You try
Name the data type: (i) my years in school; (ii) number of full years in school; (iii) number of goals scored.
Numbers or groups? Counts or a range?
(i) measured on a range → numerical continuous
(ii) whole count → numerical discrete
(iii) whole count → numerical discrete
continuous, discrete, discrete
That’s Statistics.
Mean, median, mode and range — the everyday tools for a set of data.