Added methods ex1, ex2, and ex3
Added tests to check whether ex1 returns the number of elements in a given array, whether ex2 returns the second element in a given array, and whether ex3 returns the sum of a given array of numbers
Added ex4 method to find the max number in a given array
Added test to check whether ex4 returns the max number in a given array
Added methods ex5,ex6,ex7,ex8,ex9
Added tests for ex5 - ex9