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Averages. Objectives Recap types of averages, and how to calculate them. Find the mean , median and mode from frequency tables. Averages. The ‘ normal ’ average The ‘ middle ’ average The ‘ favourite ’ average. Add them up and divide by how many there are. Mean Median Mode. - PowerPoint PPT Presentation
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Averages
Objectives• Recap types of averages, and how to
calculate them.• Find the mean, median and mode from
frequency tables.
Averages• Mean
• Median
• Mode
The ‘normal’ average
The ‘middle’ average
The ‘favourite’ average
Add them up and divide by how many there are
Put them in order and choose the middle one
The most common or most popular value
There once was a woman from DundeeWhose age had last digit threeIf her whole age reversedIs the square of the firstThen what must the woman's age be?
A Dozen, a Gross, and a ScorePlus three times the square root of fourDivided by sevenPlus five times elevenEquals nine squared and not a bit more.
What length of word is the most
common?
There once was a woman from DundeeWhose age had last digit threeIf her whole age reversedIs the square of the firstThen what must the woman's age be?
Letters Frequency1 12 43 94 65 76 37 08 1
Mode:
3
What length of word is exactly in
the middle?
There once was a woman from DundeeWhose age had last digit threeIf her whole age reversedIs the square of the firstThen what must the woman's age be?
Median:
4
If they were shared out equally, how many letters to a
word?
There once was a woman from DundeeWhose age had last digit threeIf her whole age reversedIs the square of the firstThen what must the woman's age be?
Mean:
3.9
Mode from a Frequency Table
1) Identify the category with the largest frequencythe category itself is the mode
Median from a Frequency Table
1) Complete a ‘cumulative frequency’ columnthis is a running total of the frequencies
2) Determine the middle value(total + 1) ÷ 2
3) Identify the category containing the middle valuethe category itself is the median
Mean from a Frequency Table
1) Complete a ‘frequency x class’ columnthis gives the total of the items for each category
2) Find the total of this column, and the frequencythese are the totals needed for the mean
3) Divide total ‘frequency x class’ by total frequencythe number you calculate is the mean
A Dozen, a Gross, and a ScorePlus three times the square root of fourDivided by sevenPlus five times elevenEquals nine squared and not a bit more.
Joint mode: 4 and 5
Median: 4
Mean: 3.93333...
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