Answer
a) 12/24 = 1/2
b) 12/24 = 1/2
c) 8/24 = 1/3
d) 6/24 = 1/4
e) 6/24 = 1/4
Work Step by Step
The above answers follow quickly from listing out the permutations:
1234, 1243, 1324, 1342, 1423, 1432, 2134, 2143, 2314, 2341, 2413, 2431, 3124, 3142, 3214, 3241, 3412, 3421, 4123, 4132, 4213, 4231, 4312, 4321.