Question (20 marks)
For this task you will create a class containing a number of methods for processing an array
of marks, which are scores in a test. Each mark is an integer in the range 0 to 100 inclusive.
On the Interact site for this subject, you have been provided with a class Marks (in Project2
code zipped folder), which has a method getMarks that returns an array of marks for you to
use in testing.
The class ProcessMarks that you create will have the methods specified below. Most will
accept an array of marks as an argument; one will accept an array of characters. The return
type should be appropriate for the returned value.
The max, min and range methods will return the maximum mark, the minimum mark
and the difference between the maximum and minimum marks respectively.
The mean and stdDev methods will return the mean and standard deviation of the set
of marks. Your textbook contains a description of how these can be calculated.
The median method will return the median value of the set of marks. The median
value is the middle one when the values are placed in order. To obtain an ordered
version of the marks you may use an appropriate sort method of the Java API’s Arrays
class. Be careful not to destroy the original array of marks. If there is an even number
of marks, the middle value is taken as the average of the two values that are nearest
to the middle.
The mode method will return the mode of the set of marks, which is the most
commonly occurring mark. To find the mode, use an ordered version of the set of
marks, as used for finding the median. If there is more than one value that is most
common, any one of the most common values will do for the mode.
The grades method will return an array of characters, which are the grades
corresponding to the integer marks in the array of marks. The grades are to be
assigned using the following lower boundaries for the corresponding marks: for grade
A, the lower boundary is 85; for grade B, it is 75; for grade C, it is 65; for grade D, it is
50; and E is the grade for all other marks. A best solution for this method would not
have the values for the lower boundaries hardcoded but would use an array for these
values, which would allow the grade boundaries to be altered.
The gradeDistn method will accept an array of characters, which are the grades
assigned for the array of marks, such as returned by the grades method. The
gradeDistn method will return an array of integer values containing the distribution of
grades, which is the number of occurrences of each grade in the assigned grades. The
characters used for grades are fixed. The returned array should provide the
distribution in order from grade A to grade E.
The following points should be taken into account in the design of your program:
None of your code should change the contents of the original array of marks.
You should not make any assumption that the client code, that would use your
methods, should call them in any particular. That is, you should not assume that a
client that calls the range method will have previously called the max and min
methods.