Three numbers are selected from the set `{1, 2, 3, ..., 23, 24}`, without replacement. The probability that the selected numbers form an A.P. is equal to

A number is selected from the set {1, 2, 3,.., 20} . The probability That the selected number is divisible by 3 or 4 is

A number is selected from the set {1,2,3, . . .20}. The probability that the selected number is divisible by 3 or 4 is . . .

Three integers are selected simultaneously from the set of integers {1,2,3,...,50 .The probability that the selected numbers are consecutive is equal to

Three numbers are selected simultaneously from the set (1,2,3,...,25). The probability that the product of the selected numbers is divisible by 4 is equal to