1 Average A single number which FAIRLY represents a group of other numbers. There are 3 types of average ( 3 different ways of working out an average number ) Menu
Dec 30, 2015
11
AverageA single number which FAIRLY represents a group of other numbers.
There are 3 types of average ( 3 different ways of working out an average number )
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22
MEAN
MEDIAN
MODE
Add up all the numbers and then divide by how many numbers there are.
Put the numbers in order of size and then find the middle number.
The number which appears most often.
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44
MEAN
Add up all of the numbers and then divide by how many numbers there are.
Maths----- 72 %
English--- 56 %
History----60 %
French----55 %
Science-- 86 %
72
56
60
55
86
+
329329
5= 65.8 %
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66
Median Median (Put in order of size then find the middle number)(Put in order of size then find the middle number)
44 22 77 88 11 1212 99
Median = 7Median = 7
1313
7 + 8 7 + 8
22= 7.5= 7.5
What if there is an even number
of numbers ?
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77
Another Method of Locating The Median From Raw Data
2, 3, 3, 3, 5, 7, 8, 9, 9, 11, 12, 14, 14, 15, 18
Firstly count how many numbers there are in the list.
15 Then ADD 1 and divide by 2+ 1
2= 16
2
= 8th number.
Now count to it.
Median = 9
What if there is an even number
of numbers ?
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88
What if there is an even number
of numbers ?
3, 5, 7, 11, 11, 13, 15, 21, 22, 23, 26, 30
Count how many numbers there are:
12Then ADD 1 and divide by 2
+ 12
= 13
2
= 6.5th number
Between the 6th & 7th numbers
Median = 14
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1010
Mode (Modal Average)Mode (Modal Average)(The number/data which appears most often)(The number/data which appears most often)
Ex1) 3, 5, 2, 5, 3, 2, 4, 1, 3Ex1) 3, 5, 2, 5, 3, 2, 4, 1, 3 Ex2) 12, 14, 14, 15, 11, 15, 16, 10Ex2) 12, 14, 14, 15, 11, 15, 16, 10
Ex3) 1, 0, 2, 1, 0 ,2, 3, 3 Ex3) 1, 0, 2, 1, 0 ,2, 3, 3
Mode = 3Mode = 3
Mode = 14 & 15Mode = 14 & 15
No ModeNo Mode
MenuAnswers
1212
So anybody with a small range must be clever ?
The RANGEHighest number – Lowest number
What does it show ?
Paul’s exam marks:
Maths 89%
Science 90%
English 90%
History 88%
French 91%
Range: 91- 88 = 3
David’s exam marks:
Maths
Science
English
History
French
Range = 3
?
?
?
?
?
4%
3%
6%
5%
4%
Small RangeConsistent
ReliablePredictable
David must be clever !Obviously
not !
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