1. Explain the difference between a Compiler and Interpreter? 2. Explain the structure of a Java Program with the help of an example? 3. Identify the errors in the following Java program and rewrite the program without errors a. public class JavaDemo { public static main(String[] args) { System.out.println("Hello World Example) } } b. public static void main(String[] args) string nn="AMAIUB" } } int year=-2018; system.out.println("University Name : "+NN) system.out.println("Current Year :"year); 4. Write a java program that assigns 1.5, 22.4, 0.333 and 1.123 to the variables a, b, c and d respectively. Next compute their sum. Assign the result to a variable named sum. Next compute the average of the values in these variables. Assign the result to a variable named average. Display the values in sum and average with appropriate labels.