Combinatorics and Probability

Practices

• Probability Questions@geeksforgeeks
• Sawaal aptitude-reasoning
• JEE example
• Probability of Non-Consecutive Cards
• Probability of being dealt a pair in a poker hand
• Probability Interview Questions & Answers for Data Scientists

Good examples

• Words of length 10 are formed using the letters A, B, C, D, E, F, G, H, I, J. Let x be the number of such words where no letter is repeated; and let y be the number of such words where exactly one letter is repeated twice and no other letter is repeated. $\frac{y}{9x}=?$
• How many ways to draw 5 cards from a deck and get at least a pair?
• How many ways to draw 5 cards from a deck and get two pairs?

Books

• One Thousand Exercises in Probability: Third Edition
• Fifty Challenging Problems in Probability with Solutions (Dover Books on Mathematics)
• 100 Questions (and Answers) About Statistics (SAGE 100 Questions and Answers)