A university wishes to estimate how satisfied students are with a certain course. They make a survey, and ask students to complete it. 105 of the 400 students on the course return the survey. The mean score for the course is 7.6. From previous studies, the university knows that the population standard deviation for responses is around 1.3. (a) Construct a 99% confidence interval for the true level of average student satisfaction. (b) If more of the students had returned to survey, would the confidence interval be wider or narrower? Explain your answer (c) Why might your answer in a) be biased?