Create FindAverage.java

add a findAverage java file in maths directory

Maths/FindAverage.java

@@ -0,0 +1,25 @@
+package Maths;
+
+public class FindAverage {
+
+    //Driver
+    public static void main(String[] args) {
+        int[] array = {2, 4, 10};
+        assert findAverage(array) == 5;
+    }
+
+    /**
+     * find average value of array
+     *
+     * @param array the array contains element and the sum does not 
+     * excess long value limit
+     * @return average value
+     */
+    public static int findAverage(int[] array) {
+        long sum = 0;
+        for (int i = 0 ; i < array.length; ++i) {
+            sum += array[i];
+        }
+        return (int)(sum / array.length);
+    }
+}