the last part of the problem

Write a function wrand(w) which takes as input a number from 0 to 100 and as output returns 1 with likelihood w% and returns-1 with likelihood (100-w)%. For example, if you evaluate wrand(70.8) one hundred thousand times, you should see approximately 70,800 Is and 29,200 Is. (Make sure your function works even if w is not an integer.)