A European cereal maker recently sampled 20 of its medium-size oat cereal packages to determine the weights of the cereal in each package. These sample data, measured in ounces, are as follows:

14.7 16.3 14.3 14.2 18.7 13.2 13.1 14.4 16.2 12.8 13.6 17.1 14.4 11.5 15.5 15.9 13.8 14.2 15.1 13.5 Calculate the first and third quartiles for these sample data.