Measures of Variability
determine how "spread out" or varied" a set of data is.
Range: the difference between the largest and smallest value in a set of data.
EXAMPLE: find the range of ages of people in our class
highest value:
lowest value:
RANGE:
with teacher MR K. 39 yrs old.
highest value: 39
lowest value:
RANGE:

Robin can drive to university using the downtown route or the perimeter
route. The downtown route is shorter, but it has more traffic, and can
become quite crowded. The driving times in minutes for each route
(arranged in ascending order) for 5 days are shown on the table below.
Downtown Route 15 26 30 39 45
Perimeter Route 29 30 31 32 33
Which route should she take?

The mean math marks and standard deviation for two classes are shown
below. Assume that 68 percent of the marks in each class are within
one standard deviation of the mean mark.
mean mark (μ) standard deviation (σ)
Class A 74 4
Class B 72 8
1. In which class is the set of marks more dispersed?
2. Bert in Class A and Beth in Class B each have a mark of 82%.
How many standard deviations are they from their class means? Who
appears to have the better mark?