Write a program called GradeCalculator that allows the user to enter the averages for a given number of students and outputs their grades as shown below, using 90, 80, 70, 60 for the cutoffs for A, B, C, D. Enter number of students: 4 Enter average for student 1: 35 Grade for student 1: F Enter average for student 2: 98 Grade for student 2: A Enter average for student 3: 75 Grade for student 3: C Enter average for student 4: 86 Grade for student 4: B The program should have a main method that prompts the user for the number of students. prompts the user for the average for each student. calls the method below passing it the average entered by the user. This method should return the students grade as a String: String calculateGrade (double average) { } outputs the String returned by the calculateGrade() method.