1. Chapter 36 Averages & Range

2. Types of Average  Range = largest- smallest  Mode = most common  Median = middle (when put in order)  Mean = total ÷ number

3. Example  The price of a can of cola in different shops is: 33, 34, 31, 32, 30, 31, 31, 35p Find(a) the range (b) the mode (c) the median (d) the mean

4. Discrete Frequency Distribution  Mode = value with highest frequency  Mean = Σfx ÷Σf Example The number of goals scored by a team are Number of Goals 0 1 2 3 4 5 Number of Games 4 3 4 2 3 1

5. Grouped Frequency Distribution  Find the mid-point of the group for the x value Example The masses of a group of children are Example Mass (kg) Freq 40≤m<50 50≤m<60 60≤m<70 70≤m<80 310612

6. Ex 36.3 Q1 SalaryMid-pointFreq f × x 10≤s<15 15≤s<20 20≤s<25 25≤s<30 30≤s<35 12.517.522.527.532.579321402987.5560315054 Σf=127 Σfx=1916.5 Mean = 1916.5÷127 = 15.1

7. Comparing Distributions  Compare these marks out of 10 between girls and boys Mark 7 8 9 10 Number of boys 2 5 3 0 Number of girls 4 0 2 1

8. Which is the Best Average? A youth group leader gets a discount if she buys all cans the same size. She took a vote on which size people wanted. Which size should she buy? Size (ml) 100 200 330 500 Votes 9 12 19 1