An econometrics class has 80 students, and the mean student weight is \(145 \mathrm{lb}\). A random sample of 4 students is selected from the class, and their average weight is calculated. Will the average weight of the students in the sample equal \(145 \mathrm{lb}\) ? Why or why not? Use this example to explain why the sample average, \(\bar{Y}\), is a random variable.