RANDOM VARIABLES
PART 1 Discrete random variables
PART 2 Combining random variables
PART 3 Binomial random variables
PART 4 Geometric random variables
PART 5 Law of large numbers
COUNTING, PERMUTATIONS, AND COMBINATIONS
PART 1 Counting principle and factorial (计数原理与阶乘)
Part 2 Permutations (排列)
Part 3 Combinations (组合)
Part 4 Combinatorics and probability