According to a 2014 research study of national student engagement in the u. s., the average college student spends 17 hours per week studying. a professor believes that students at her college study less than 17 hours per week. the professor distributes a survey to a random sample of 80 students enrolled at the college. from her survey data the professor calculates that the mean number of hours per week spent studying for her sample is 15.6 hours per week with a standard deviation of 4.5 hours per week. the professor chooses a 5% level of significance. what can she conclude from her data?