1) Write a bin2Dec(String binaryString) method that converts a binary string into a decimal number. Implement the bin2Dec method to throw a NumberFormatException if the string is not binary String. 2) Design a Circle class that has radius and color as attributes and allow the setRadius method to throw an IllegalArgumentException if the radius is negative. 3) Write a program that reads unknown number of students from file named students.txt, the data stored in this file as following: Ahmad 908578 Musa 768084 Salam 859099 Then calculate the average of each student and save the results on a file named output.txt as following: Ahmad 84.3 Musa 80 Salam 91.3