1. Averages
Alevel Stats 1 with Liz

2. Qualitative (Categorical)
Types of data
Qualitative (Categorical)
Data that uses words.
e.g. What’s your favourite food? Pizza!
Quantitative
Data that uses numbers.
e.g. How many sisters do you have? 2
Discrete
Data that can be counted.
e.g. How many tvs are in your house? 2
Continuous
Data that is measured.
e.g. How tall are you? 165 cm

3. Key terms Stats Notation
Mean: add up all numbers and divide by how many there are.
Median: put numbers in order and find the middle. If two middle numbers occur, add them and divide by two (find the midpoint of the two numbers).
Mode: the number that occurs most frequently. If there is a tie, it is bimodal and you list both numbers. If nothing repeats, there is no mode.
Stats Notation
- The total number of items of data
- Represents the value of each item
- Greek symbol “sigma” which means to sum or “add up”
- Read as “x bar” and is the symbol used for the mean.

4. Averages

5. Seeing Stars!!!

6. How many stars do you think there were?
Guesses:
Calculate the following averages:
Mean:
Median:
Mode:
There were 118 total! 

7. Using your graphical calculator:
The following are the goals scored in each match by Arsenal Ladies in : 5,4,3,3,3,3,2,1,4,6,3,0,5,0,1,4,3,10 Find the mean, median, and mode score.
Change settings to match the screen below & press EXE, then click SET 1VAR (F1)
Enter data in List 1, click Calc (F2), then click SET (F6)
Select Menu then Stat
Here are the answers!
Entering the data:
Thus, the mean is 3.33, the median is 3, and the mode is 3.

8. Averages from frequency tables
A fashion store sells dresses in different sizes.
This data shows the number of varying sizes of a dress that are sold in a week.
Find the mode, mean and median of the data.
Which average will the store manager be most interested in? Why?

9. Frequency tables in your graphical calculator
Choose Calc then Set. Change the settings to match the following & press EXE
Enter data in List 1 and frequency of each in List 2
Choose 1VAR and find the answers!
Thus, the mean is 11.47, the median is 12, and the mode is 12.

10. Grouped data may appear in a HISTAGRAM
Similar to bar charts but the bars can have different widths
Frequency of the data is measured by the area of each bar, not its height
Formula for finding the height of each bar in a histogram:

11. Grouped data
Complete the frequency densities in the following table. The first one’s been done for you.
Hints:
Width is found by finding the span of each group of data
Freq Den =

12. Grouped data
A botanist measures the lengths of willow leaves, obtaining the results summarized in the table.
Length, x cm
Frequency, f
Draw a histogram representing the data.
Find the estimated mean, median, and modal leaf length.

14. Independent Study Stats Textbook Pg. 8, Exercise 1A
Pg. 14, Exercise 1C (#1 – 6)