a. Create a histogram showing the change in BDI scores from baseline to 12 weeks. Comment on the shape of the distribution. [1.5 Marks] b. Based on the sample data, can you conclude that the mean change in BDI at 12 weeks was at least 13? Let a=0.05. Show all calculations. [2.5 Marks] c. Using the sample data, determine the proportion of observations that fall within 2 standard deviations of the mean change in BDI from baseline to 12 weeks. How does this compare to what you would expect the proportion to be based on your observations about the shape of the distribution from question a? Explain. [2 Marks]