Zinfandel is a popular red wine varietal produced almost exclusively in California. It is rather controversial among wine connoisseurs because its alcohol content varies quite substantially from one producer to another. In May 2013, the author went to a certain website, randomly selected 10 zinfandels from among the 325 available, and obtained the following values of alcohol content (%). 14.8, 14.5, 16.1, 14.2, 15.9
13.7, 16.2, 14.6, 13.8, 15.013.7, 16.2, 14.6, 13.8, 15.0

Required:
Calculate the sample variance using the shortcut formula after subtracting 13 from each observation.