Using the direct method for arithmetic mean, sum the observations: 10 + 19 + 22 + 16 + 15 + 18 + 20 + 18 + 14 + 18 + 23 equals 193. Divide this sum of 193 by the total of 11 observations to get the mean. The result is 17.545, which rounds to 17.55. The mean is 17.55.