There are 4 questions. Please help and provide explanations if possible. Thanks!

1. The Playground class (algs13) represents a linked-list of doubles, illustrated below. first 5 13 18 12 5 An instance could be created as: Playground hw4 = new Playground(); Assume that the instance is somehow populated with data (as in the above figure). Write an instance method of the Playground class that would compute the difference between the maximum and minimum values of a Playground instance. (the answer for the above figure would be: 18-5 = 13) a) Show how to call your function; use hw4 as the invoking instance. b) Write the function here. 2. Show the output of the function call: Stdout.println( recur(5) ); public static String recur(int n) { if (n