how to solve

Keep using the data set for this question and the next 4 questions: In the study of Schizophrenia, researchers measured the activity of the enzyme monoamine oxidase(MAO) in the blood platelets of 18 patients. The results (in moles) are as follow: 4.1 5.2 6.8 7.3 7.4 7.8 7.8 18.4 9.7 9.9 10.6 10.7 11.9 12.7 14.2 14.5 18.8 What is the value of the sample quartile 3? (answer should be in decimal form, rounded to 1 decimal place]