4.7 Sampling considerations. A statistics class has 10 graduate students and 40 undergraduate students. You want to randomly sample 10% of the students in the class. One graduate student and four undergraduate students are selected at random. Which of the following is not correct?
(a) Because each student has a 10% chance of being selected, this is a simple random sample.
(b) Because each sample includes exactly one graduate student and four undergraduate students, this is not a random sample.
(c) It is possible to get a sample that contains only graduate students.
(d) It is possible to get a sample that contains only undergraduate students.