added Letter Grade converter functionality

BMI.java

@@ -0,0 +1,37 @@
+
+public class BMI extends GaddisChallenges {
+
+    private double userWeight; //pounds
+    private double userHeight;  //inches
+    private double userBmi;
+    private String weightStatus;
+
+    public void start() {
+
+        collectInfo();
+
+        userBmi = userWeight * 703/(userHeight * userHeight);
+
+        if (userBmi >= 18.5 && userBmi < 25) {
+            weightStatus = "optimal";
+        }
+        else if (userBmi < 18.5) {
+            weightStatus = "underweight";
+        }
+        else if (userBmi > 25) {
+            weightStatus = "overweight";
+        }
+
+        print("Based on your height and weight, your BMI is " 
+        + userBmi + " so your weight is " + weightStatus);
+
+    }
+
+    private void collectInfo() {
+        print("What is your height? ");
+        userHeight = scan.nextDouble();
+        print("What is your weight? ");
+        userWeight = scan.nextDouble();
+    }
+
+}

GaddisChallenges.java

@@ -1,5 +1,11 @@
 import java.util.Scanner;
 
+/*
+future additions:
+- threading
+- GUI
+*/
+
 public class GaddisChallenges {
 
     private Scanner scan = new Scanner(System.in);
@@ -13,7 +19,15 @@ public static void main(String[] args) {
 
         print("Question 2: Magic Dates");
         MagicDates mc = new MagicDates();
-        mc.start()
+        mc.start();
+
+        print("Question 3: Body Mass Index");
+        BMI bmi = new bmi BMI();
+        bmi.start();
+
+        print("Question 4: Test Scores and Grade");
+        LetterGrades lg = new LetterGrades();
+        lg.start(); 
     }
 
     private void print(String text) {

LetterGrades.java

@@ -0,0 +1,40 @@
+public class LetterGrades {
+
+    private int numTests = 3;
+    private double[] testGrades[];
+    private double average; 
+    private char letterGrade; 
+
+    public void start() {
+
+        collectInfo();
+
+        calculateAverage(); 
+
+        calculateLetterGrade();
+
+        print(" You average is " + average + "and you letter grade is " + letterGrade);
+
+    }
+
+    private void collectInfo() {
+
+        for (int i = 1; i <= numTests; i++) {
+            print("What was your grade on Test " + i + "?")
+            testGrades[i] = scan.nextDouble();  
+        }
+
+    }
+
+    private void  calculateAverage() {
+        int sumTestGrades = 0;
+        for (int i = 1; i <= testGrades.length; i ++) {
+            sumTestGrades += testGrades[i]; 
+        }
+        average = sumTestGrades / numTests;
+    }
+
+    private void calculateLetterGrade() {
+
+    }
+}