Try something like this:
randomquestion.xlsx (8.5 KB)
Basically, generate a random number using random(), and then use this value in relevant expressions on each question to determine whether to display that question or not. If the ranges are mutually exclusive - eg 2 questions, with <0.5 and >=0.5 - then only one question will get displayed. You can optionally adjust the ranges to change the weight/frequency each question appears...