Assume that I got a $0 coin in my coin collection and my coin collection includes c={0 to 9} and is stored in a box. I took 3 coins randomly(without putting them back) and see the coins. What is the probability that the sum of these 3 coin numbers is an even number not less than 10 ? I am looking for analytical solution rather than numbers. It would be great if we get an equation, and the equation should work for any set such as c ={0 to 99}