A school principal wants to estimate the average number of hours per week students spend on homework. She surveys 50 students who are currently in the school library after classes. For these 50 students, the average number of hours spent on homework was 15 hours per week. Which of the following statements must be true?
The average number of hours spent on homework by all students in the school is 15 hours per week.
The sample size of 50 students is too small to make any valid conclusions about the entire school.
The sampling method is flawed and may produce a biased estimate of the average number of hours students spend on homework.
The sampling method is appropriate and is likely to produce an unbiased estimate of the average number of hours students spend on homework.
