How to take an array and convert all numbers to other numbers. 'JAVA'

I am trying to make a GPA calculator in java. Once I have all the grades in my array I would like to have another array that puts all the GPA's into the same size array. For example arrayA = [90, 95, 80, 87, 100] .... I want to be able to convert those numbers to arrayB and make it equal [3.7, 4.0, 2.7, 3.3, 4.3]

Here is what I have so far:

import java.util.Scanner;
import java.util.Arrays;
/**
 Coleman Strauss
 GPA Calculator
 March 12, 2015
 */
public class GPACalculator
{
    public static void main (String[] args) 
    {
        int numClasses;
        Scanner scan = new Scanner(System.in);
        double[] myArrayGrades;
        double[] myArrayGPA;


        System.out.println("Please enter in the amount of classes you have:   ");
        numClasses = scan.nextInt();

    System.out.println("Alright so you have " + numClasses + " classes.");

    myArrayGrades = new double[numClasses];

    for (int i=0; i < numClasses; i++) {
        System.out.println("Please enter all your grades in a row!");

    }

    System.out.println(myArrayGrades);




}

}