Baker Ltd is concerned about the influence on petrol prices on its profit margins. The owner of

Question:

Baker Ltd is concerned about the influence on petrol prices on its profit margins. The owner of the company looked at weekly petrol prices (pence per gallon) for London and compiled a time series. The series starts on 14 November 2005 and goes until 4 August 2008. The data in pence per gallon are shown in Table 9.14.

The owner is not too familiar with forecasting, but knows how to use trending function. Put yourself in his shoes and do the following:

(a) Chart the time series

(b) Pick the best suitable curve to fit to the data set

(d) Calculate the confidence interval

(e) What do you think you need to do to preserve your profit margins?

250.1 238.6 291.5 269.1 249.7 296.2 296.1 330.9 334.2 423.8 241.6 244.3 287.9 261.5 302.6 293.2 331 335.7