1. Topic 6: Statistics

2. 6.1 Discrete data: can be counted Continuous data: can be measured
# of heads when flipping a coin
# of red cars in a parking lot
Continuous data: can be measured
Weight, height, time
Express continuous data to a sig. fig.

3. Together
P. 285 #1

4. 6.2 Frequency Tables and Polygons
Keep track of how often a value occurs
discrete

5. Example
60 students from grade 9 are asked to pick a number between 0 and 4. The result is shown here. Represent the information in a frequency table.

6. Frequency Polygons
Continuous data
Line graph
Draw it on GDC

7. Example
Time (t min.)
Frequency 3 42 6 23 9 8 12 5 15 18 4 21 24 2 27
The table shows the time, in minutes to the nearest three minutes, of 100 telephone calls made from the same cell phone in one month.
Draw a frequency polygon. GDC

8. Grouped Data and Continuous Data
Use histograms and stem plots to group data
Useful when the data has a wide spread
Use for discrete or continuous

9. Example
A survey was carried out in a shopping mall to find out how old people were when they passed their driving test people between the ages of15 and 92 were interviewed and the results are in the table.
Why would grouping this data be a good idea?
Age (x)
Frequency
15≤ x < 25 85
25≤ x < 35 33
35≤ x < 45 14
45≤ x < 55 8
55≤ x < 65 3
65≤ x < 75 34
75≤ x < 85 2
85≤ x < 95 1

10. Mid-interval Values Find by summing end values and dividing by 2
Ex = 40 ÷ 2 = 20

11. Upper and Lower Boundaries
Discrete
Lower value in class interval = lower boundary
Upper value = upper boundary
Continuous
Calculate by averaging upper value of one group with lower value of next group

12. Example Using the table find the upper boundary of first interval.
What is the lower boundary for the second interval?
What would the intervals now look like?
Age
Frequency
0-9 8
10-19 12
20-29 15
30-39 6

13. Frequency Histograms Visual way to represent data
Equal class intervals
No space between bars
Label axes.
Look at p. 288 Frequency Histogram

14. Stem and Leaf Diagram Orders the data One digit behind stem
Provide a key
Ex = 12.5

15. Example
These are the times taken (in minutes) for 50 batteries to run out.
Construct a stem and leaf diagram

16. Back-to-back stem and leaf diagram
Look at page 289
Assignment: p #1, 3, 4,5,6, 7, 8