Sugar prices. The price of sugar f luctuates in the world market. Here are the prices (£/tonne) for the years 2008–2012.

2008 2009 2010 2011 2012 0.39 0.37 0.29 0.21 0.20

a) Find a 3-year moving average (MA) prediction for the price in 2013.

b) Find a prediction for 2013 with an exponential smoothing model, with a = 0.5.

c) The actual price of sugar in 2013 was £0.21 per tonne (you can find current prices at www.imf.org/external/np/
res/commod/table3.pdf.) Compute the absolute percentage error for each prediction.