Lesson:

• We will be working on a new unit starting today.

• First define the following words: mean, median, mode and range.

Mean:

The mean is the average of the numbers: a calculated "central" value of a set of numbers.

To calculate: Just add up all the numbers, then divide by how many numbers there are.

Ex: what is the mean of 2, 7 and 9?

Add the numbers: 2 + 7 + 9 = 18

Divide by how many numbers (i.e. we added 3 numbers): 18 ÷ 3 = 6

So the Mean is 6

Median:

The middle number (in a sorted list of numbers).

To find the Median, place the numbers you are given in value order and find the middle number.

Example: find the Median of {13, 23, 11, 16, 15, 10, 26}.

Put them in order: {10, 11, 13, 15, 16, 23, 26}

The middle number is 15, so the median is 15.

(If there are two middle numbers, you average them.)

Mode:

The number which appears most often in a set of numbers.

Example: in {6, 3, 9, 6, 6, 5, 9, 3} the Mode is 6 (it occurs most often).

Range:

The difference between the lowest and highest values.

In {4, 6, 9, 3, 7} the lowest value is 3, and the highest is 9, so the range is 9 − 3 = 6.

Make sure that every student copies these in their notebooks. The Swedish translations are the following:

• Mean - Medelvärde

• Median - Median

• Mode - Typvärde

• Range - Värdemängd

• A good strategy is to list the numbers from the least to the latest. That will make sure that don’t skip any and make finding the range, mode and median easier. Cross them off as you use them.

Work In Class:

Page 11 (Range & Median)

Q. 1 - 11

Page 14 - 16

Q. 1 - 14

Use this website for more work.

Support:

• Watch these videos

Extension:

• There are addition problems here.

• For more difficult sets of numbers use this worksheet.

• challenge problems

Conclusion:

• Review the following terms and how to find them:

• Mean

• Median

• Mode

• Range