An experiment was conducted to determine the effect of baking temperature on chocolate cake quality; no cakes were baked at low temperature, n¡ cakes were baked at medium temperature and

n2 were baked at high temperature. For each cake the volume was measured. (a) Write down a suitable linear model for analysing these data and express it in matrix form, using centred parameterisation. [5 marks] (b) Find the least squares estimators of the parameters of the model for this experiment, making clear the notation you use. [5 marks]