Create a simple Node.js server that listens on port 3000 and responds with "Hello, World!" for all incoming HTTP requests. You can use any library or framework of your choice.
Write a function in Node.js that takes an array of integers as input and returns the sum of all the numbers.
Create a Node.js script that reads a text file named "data.txt" and counts the number of words in it. The script should print the total word count to the console.