A: 4 / 24 (or 1/6) B: (24 - 3) / 24 = 21/24 (or 7/8) C and D: Theoretical probability for each number is 1/6 on each roll, and we expect 4 occurrences of each number, on average. 2 came up as expected. 6 came up 3/4 as often as expected. Or "Not-6" came up 21 instead of 20 times, slightly more often than expected.
