(Modifying Class GradeBook)Modify class GradeBook (Figs 1,2.) as follows:a) Include a seco...

(Modifying Class GradeBook)Modify class GradeBook (Figs 1,2.) as follows:

a) Include a second string data member that represents the course instructor’s name.

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b) Provide a set function to change the instructor’s name and a get function to retrieve it.

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c) Modify the constructor to specify course name and instructor name parameters.

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d) Modify function displayMessage to output the welcome message and course name, then the string "This course is presented by: " followed by the instructor’s name.

Figure 1 GradeBook class definition containing function prototypes that specify the interface of the class.

Figure 2 GradeBook member-function definitions represent the implementation of class