A professor's rule of thumb is that students should spend 2 hours studying for each 1 hour spent in class. Professor Bob teaches a class that meets 3 hours per week. He randomly selects 8 students and finds that they study the following amounts per week: 1, 2, 4, 4, 6, 6, 8 and 14. Assuming a normal distribution, can the professor conclude with 95% certainty that the students are studying as they should?