Wind speed data has been collected from two different weather stations over the course of fifty days of stormy weather.

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Rockall

Raw data is collected from Rockall- the wind speeds, measured inkm/hon the fifty days in the study are recorded, in ascending order, in the table below:

23 24 26 29 30

30 34 35 38 39

42 46 47 48 49

49 50 51 51 53

53 55 56 58 59

61 62 64 65 68

68 68 69 70 73

74 74 75 77 81

81 82 85 86 89

90 90 91 94 95

Find the mean, mode and median wind speeds, and comment on your findings.

Use Excel to find the standard deviation of the wind speeds, and explain its relevence.

Find the upper and lower quartiles of the data, and use them to draw a box and whisker diagram of the wind speeds. Use a scale that goes up to 130km/hso that you can fit the second data set on it also.

20 Marks

North Utsire

The wind speed data from North Utsire is given as grouped data:

Wind speed (wkm/h)

30 w< 40

40 w< 50

50 w< 60

60 w< 70

70 w< 80

80 w< 100

100 w< 130

Frequency

15

12

8

4

2

6

3

Find the mean wind speed.

Draw a histogram to represent the distribution of wind speeds.

Create a cumulative frequency table, and from it, draw a cumulative frequency curve. Use the curve to find the median and upper and lower quartiles.

What do the mean, median and quartiles tell you about the distribution of wind speeds in North Utsire?

Use the median and quartiles to draw a box and whisker diagram on the same scale as the one for Rockall.

20 Marks

Analysis and Comparison

What conclusions can be drawn from the measures of central tendency for Rockall and North Utsire?

What differences are there between the quartiles for Rockall and North Utsire? What can you conclude from these differences?

How is this shown by the Box and Whisker Plots? What extra information do those graphs give you?

What overall conclusions can be made about the weather conditions in Rockall and North Utsire?

Describe what else the various calculations and graphical representations have told you about the wind speeds in North Utsire and Rockall.

Draw comparisons between the two weather stations.