Assume that (i) the size of each disk block is 8KB, (ii) the probability that the buffer manager can handle a data request without accessing the disk (i. e., the probability that a requested block is already in the buffer) is 90%, (iii) only 10% of disk block accesses require a disk seek (i. e., 90% of the disk blocks are read consecutively without requring any disk seek), (iv) no disk blocks are updated (i. e., no need to write dirty blocks back to the hard drive), and (v) the time spent for reading/writing data in the main memory is negligible (considered 0 milliseconds). Under these assumptions, calculate the expected data access time (i. e., how much time it would on average take to obtain a disk block from the buffer manager).

8. create an abstract student class for parker university. the class contains fields for student id number, last name, and annual tuition. include a constructor that requires parameters for the id number and name. include get and set methods for each field; the settuition() method is abstract. create three student subclasses named undergraduatestudent, graduatestudent, and studentatlarge, each with a unique settuition() method. tuition for an undergraduatestudent is $4,000 per semester, tuition for a graduatestudent is $6,000 per semester, and tuition for a studentatlarge is $2,000 per semester. write an application that creates an array of at least six objects to demonstrate how the methods work for objects for each student type. save the files as student.java, undergraduatestudent.java, graduatestudent.java, studentatlarge.java, and studentdemo.java.