8   3. Stav is studying the large data set for September 2015 He codes the variable Daily Mean Pressure, x, using the formula y = x − 1010 The data for all 30 days from Hurn are summarised by ∑ y = 214          ∑ y2 = 5912 (a) State the units of the variable x (1) (b) Find the mean Daily Mean Pressure for these 30 days. (2) (c) Find the standard deviation of Daily Mean Pressure for these 30 days. (3) Stav knows that, in the UK, winds circulate • in a clockwise direction around a region of high pressure • in an anticlockwise direction around a region of low pressure The table gives the Daily Mean Pressure for 3 locations from the large data set on 26/09/2015 Location Heathrow Hurn Leuchars Daily Mean Pressure 1029 1028 1028 Cardinal Wind Direction The Cardinal Wind Directions for these 3 locations on 26/09/2015 were, in random order, W          NE          E You may assume that these 3 locations were under a single region of pressure. (d) Using your knowledge of the large data set, place each of these Cardinal Wind Directions in the correct location in the table. Give a reason for your answer. (2) _____________________________________________________________________________________ _____________________________________________________________________________________ _____________________________________________________________________________________ _____________________________________________________________________________________ _____________________________________________________________________________________ _____________________________________________________________________________________ _____________________________________________________________________________________ _____________________________________________________________________________________ _____________________________________________________________________________________ _____________________________________________________________________________________