4. Helen is studying the daily mean wind speed for Camborne using the large data set from 1987 The data for one month are summarised in Table 1 below. Windspeed na 6 7 8 9 11 12 13 14 16 Frequency 13 2 2 2 2 2 Table 1 (a) Calculate the mean for these data. (1) (b) Calculate the standard deviation for these data and state the units. (2) The means and standard deviations of the daily mean wind speed for the other months from the large data set for Camborne in 1987 are given in Table 2 below. The data are not in month order. Month A B C D E Mean 7.58 8.26 8.57 8.57 11.57 Standard Deviation 2.93 3.89 3.46 3.87 4.64 Table 2 (c) Using your knowledge of the large data set, suggest, giving a reason, which month had a mean of 11.57 (2) The data for these months are summarised in the box plots on the opposite page. They are not in month order or the same order as in Table 2. (d) (i) State the meaning of the * symbol on some of the box plots. (ii) Suggest, giving your reasons, which of the months in Table 2 is most likely to be summarised in the box plot marked Y. (3)