A tree farm growing specialist acacia trees wishes to better understand the timber yield they get from harvesting the trees. A random sample of 23 trees are harvested and their yields are recorded. This appears in the table below. NB In this question, if you use Excel functions you should list the functions you used. If you use an analysis tool add-in you should cut and paste the output into your answer, and if you use and "old school" approach you should quote the relevant formulae. + Tree number Age, A Yield, Y (Years) (cubic meters) 9.5 24.2 10.4 29.2 7.2 18.2 8.9 32.5 10.5 31.2 11.3 30.5 6.7 8.3 9.2 31 8.4 23.3 10.6 31.2 7.7 23.8 11 36.2 9.3 29.1 14 11.6 23 15 9.4 35.8 16 7 15 17 7.4 17.1 18 9.1 26.9 19 8.6 28.1 20 8 22.6 21 8.2 28.1 22 9.7 34.4 23 9.6 34.8 EA = 209.3, EY = 614.5, EA? = 1947.57, EY? = 17535.41, ZAY = 5745.75 a. [3 marks] Determine the mean, median and standard deviation of timber yield for this sample. b. [2 marks] Determine the Ordinary Least Squares regression line that uses tree age to explain or predict timber yield. c. [1 mark] Interpret the slope coefficient. d. [2 marks] Determine and interpret the standard error of the estimate. e. [2 marks] Use your regression equation to predict the yield from a one year old tree, and explain why this might be problematic. f. [2 marks] Create a scattergram of the data and study it carefully. Identify and describe any features that may cause you to doubt whether a OLS linear regression model is appropriate. [NB There is no need to include the scattergram in your answer.]