14.49 The data file Brent Oil Price contains the monthly oil prices for Brent crude oil, covering the years 2012 to 2020.

a. Plot the time series of the crude oil price for the year 2012. Perform a runs test to test this series for randomness using these 12 observations.

b. Now plot the time series for all years. Perform another runs test for randomness using all 108 observations.