There are 6 people in line to board a plane with 6 seats. The first person has lost his boarding pass, so he takes a random seat. Everyone that follows takes their assigned seat if it's available, but otherwise takes a random unoccupied seat. What is the probability the last passenger ends up in his/her assigned seat, as a decimal?

20

A fair 6-sided die is rolled twice. The probability that the second roll is strictly less than the first roll can be written as a fractiona/b

, what is such fraction?

21

Two players each flip a fair coin. The probability that they get the same result can be expressed as a fractiona/b

, what is such fraction?