Maths on Wednesday.

Data Calculations: Finding the Mean (Average)

Looking at any data display graph can tell you a lot about the data, but there are some calculations you can do that will give you more information about the data, that you cannot get by just looking at a graph.

For example:  For the school fundraiser, Mya, Kura, Siunipa and Alicia have been given tickets to sell.

Names	Tickets
Mya	12
Kura	10
Siunipa	16
Alicia	14

How many tickets have the girls been given to sell altogether?

12 + 10 + 13 +  14 = 52

If they decided to sell the tickets altogether and then shared them equally among themselves, how many tickets would each one get?

52 divide by number of girls  (4)  = 13

By doing this, we are finding the ‘average’ or mean number of tickets that the girls would have.

The mean (average) number of tickets each girl would have is? 13

To find the mean for a list of scores (numbers), there are two steps.

Step 1: Add up all the scores

Step 2: Divide this total by the number of scores you added up.

For example: Find the mean of 5, 6, 7 & 10

Step 1: Add up all the scores. 5 + 6 + 7 + 10 = 28

Step 2: Divide this total by the number of scores. 28 divide by 4 = 7

Answer:  Mean (average) = 7

Task 1:

Find the mean (average) for each list of scores.

1. 5, 9    

5  + 9 = 14    14 divide by 2 = 7  mean is 7

2. 10, 16  26 divide by 2 = 13 mean 13
3. 17, 13   30 divide by 2 = 15 mean 15
4. 5, 8, 8    21 divide by 3 = 7 mean 7
5. 7, 10, 13    30 divide by 3 = 10 mean 10
6. 3, 4, 5, 8   20 divide by 4 = 5 mean 5
7. 5, 8, 10, 13   36 divide by 4 = 9 mean 9
8. 9, 9, 13, 17  48 divide by  4 = 12 mean 12
9. 10, 30, 40, 40     120 divide by  4 = 30 mean 30
10. 4, 7, 9, 12, 13  45 divide by  5 = 9 mean 9
11. 4, 5, 8, 9, 10, 12   48 divide by  6 = 8 mean 8
12. 3, 5, 6, 8, 6, 4, 7, 9   48 divide by 8 = 6 mean 6  

Extra

Each week the students in Mrs Thomas’s class are expected to read books, as part of their homework.  She hopes they will read 2 or 3 books each per week.  Last week, this is the number of books each student read.

4, 3, 2, 5, 1, 3, 4, 3, 2, 3, 4, 2   38 divide by 12 = 3 mean 3  

1. How many students in Mrs Thomas’s class?

12 students

2. Find the mean number of books read by the students in her class.

4, 3, 2, 5, 1, 3, 4, 3, 2, 3, 4, 2

3. Would Mrs Thomas be happy with the class mean?  Explain why?

Yes because she asked her class to read 2 or 3 books and working out the mean shows that the average student read 3 books each.