Average height and weight investigation
Extracts from this document...
Introduction
Investigating Data – Mansfield High School.
The first thing that I' am going to do is isolate the data of the year 7 males in order to find the average height and weight of them. There is a total of 151 boys in year 7, however it would consume too much time to find an average using so many students, therefore I' am going to use a sample. The sample which I have decided to use is called “Systematic sampling”, this is where every 4th or 10th (or any other number) is taken from a list of the target population. For Example, if your target population is every child in a school, consisting of 500 pupils and you require 25, then you can use every 20th child. However on this occasion my target population is the height and weight of the boys in year 7, there area total of 151 boys in year 7 and I have decided to select every 7th. I' am going
Middle
1.44
1.49
1.61
1.5
1.45
1.65
1.59
1.65
1.49
1.48
____
29
____
I then divided the answer (29) by the number of items of data (19)
29
___
= 1.526315789
19 (1.53)
I then decided to find the median, which is simply the middle item of data. To find the median I wrote the items of data in numerical.
I then noticed that 1.50 was the median, simply because it was in the middle.
As the appropriate items of data are now in numerical order, it would be idea to find the range, which is one single number and it's the difference between the lowest and highest value of the data. The lowest item of data being 1.36, and the highest being 1,73, therefore 
1.73
1.36
____
0.37
____ Range = 0.37
I then worked out the average weight of the boys in year 7 who were on the ample. I initially decided to work out the “mean” average. Firstly I took the weights of the boys in year 7 who were on the sample and added them all together 
44
41
45
53
32
48
33
50
45
42
47
56
51
31
51
47
46
35
40
___
836
___
I then divided the answer (836) by the number of items of data (19)
836
___ = 44
19
Conclusion
therefore 
1.75
1.30
____
0.45
____ Range = 45
I then worked out the average weight of the girls in year 7 who were on the sample. I initially decided to work out the “mean” average.
Firstly I took the weight of the girls in year 7 who were on the sample and added them all together 
53
45
39
38
40
50
45
36
51
44
45
34
38
40
52
37
57
47
40
____
831
___
I then divided the answer (831) by the number of items of data (19)
831
___ = 43.73684211
19
I then decided to find the “median” average, therefore I wrote the items of data in numerical order.
I then noticed that 44 was the median, as it was in the middle.
Next, I decided to find the range 
Highest item of dara – 57
Lowest item of data – 34
therefore 
57
34
__
23
__ Range = 23
I then decided to find the mode. To find the mode, I drew a stem and leaf diagram as I feel this is the most convenient method if identifying the “mode”  (most often occuring item of data).
The following stem and leaf diagram shows the weights of the girls in year 7 who were on the sample 
Weight  Frequency

30  986487
40  50545070
50  30127

After observing my stem and leaf diagram I came to the conclusion that there are 2 “modes” which are “40” and “45”.
This student written piece of work is one of many that can be found in our GCSE Height and Weight of Pupils and other Mayfield High School investigations section.
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