2Tvwo § 2.4 Mean, mode and median

• Wiskunde
• Middelbare school
• havo, vwo
• Leerjaar 2

§2.4 Mean, mode and median

Mean, Mode and Median

The Mean, Mode and Median are ways to describe numerical data.

QUESTION:

What are 'numerical data'?

Answer in next slide.

Numerical data are ...

Numerical data are ...

- in dutch:      gegevens in de vorm van getallen

- statistics in the form of numbers (values)

Mode

The mode is the value (numbers) with the highest frequency.

(frequency = the number of time a value appears, §2.3)

Example:

Grades from class 2R: 5, 6, 10, 8, 6, 7, 9, 5, 8, 7, 6.

Let's make a frequency table.

(You learnt how to do this in §2.3)

Mode

The mode is the value with the highest frequency.

Grades from class 2R: 5, 6, 10, 8, 6, 7, 9, 5, 8, 7, 6.

Mode

The mode is the value with the highest frequency.

Grades from class 2R: 5, 6, 10, 8, 6, 7, 9, 5, 8, 7, 6.

QUESTION:

What is the mode? 

ANS

The mode is .....

Mode

The mode is the value with the highest frequency.

Grades from class 2R: 5, 6, 10, 8, 6, 7, 9, 5, 8, 7, 6.

The mode is the grade 6 (with a frequency of 3)

Mode - another example!

The mode is the value with the highest frequency.

If there is no single value with the highest frequency, there is no mode.

Both the grade 6 and 8 have the highest

frequency (4), therefore there is no mode.

Median

The median is the middle value, when the values are sorted from smallest to largest.

Grades from class 2R: 5, 6, 10, 8, 6, 7, 9, 5, 8, 7, 6.

Median

The median is the middle value, when the values are sorted from smallest to largest.

Grades from class 2R: 5, 6, 10, 8, 6, 7, 9, 5, 8, 7, 6.

QUESTION:

What is the median in this case?

ANS

What is the median?

1. 6
2. 7
3. 8
4. there is no median

Median

The median is the middle value, when the values are sorted from smallest to largest.

Grades from class 2R: 5, 6, 10, 8, 6, 7, 9, 5, 8, 7, 6.

Sorted small-large: 5, 5, 6, 6, 6, 7, 7, 8, 8, 9, 10

The median is the grade 7.

Median-new situation!

If the number of values is even, the median is the average of the two middle numbers.

Example 1:

5, 6, 6, 7, 8, 9

Median = (6 + 7)/2 = 6.5

Mean

The mean is the average of all values. You can calculate the mean by adding up all values and dividing the result by the number of values.

Grades from class 2R: 5, 6, 10, 8, 6, 7, 9, 5, 8, 7, 6.

QUESTION:

What is the mean in this case? 

You may work it out on paper!

ANS

Mean

The mean is the average of all values. You can calculate the mean by adding up all values and dividing the result by the number of values.

Grades from class 2R: 5, 6, 10, 8, 6, 7, 9, 5, 8, 7, 6.

The mean is the grade (5 + 6 + .... + 6)/11 = 77/11 = 7.

Doing this simpler is shown in the next slide!

Mean

If you have a frequency table, you can calculate the mean by first multiplying all values with their frequency, adding up the results and dividing that result by the total of the frequencies.

The mean is the grade 77/11 = 7

Homework

• Make the exercises from §2.4 from your chosen path:

- Support: 20, S21, 22, 23, S24, 25

- Standard: 20, 21, 22, 23, 24, 25

- Challenge: 20, 21, 23, 25, C5, C6

• Correct with a red pen
• Take a few pics and
• send in your workbook in GC