This is a book of 115 challenging or interesting probability problems. The background knowledge, theories, formulas and skills are mostly covered in high school/college or 1st year university maths subjects. Although most problems can be solved within half an hour, some hard problems may require hours or even days of time to find out a solution and compute the required probability. These problems can be used in teaching examinations, mathematics competitions, analytical and computing skill assessment, or even job application interviews or tests.