Problem: the set s consists of 5 numbers : { 1 , 2,3 , 4,5 } . if all possible subsets including the null set are created and one subset is chosen at random , what is the probability that the subset has 4 or 5 as its largest number ?
Rationale: "the set s has 2 ^ 5 = 32 subsets . the number 5 is in half of these subsets . thus 5 is the largest number in 16 subsets of s . of the remaining 16 subsets , 4 is an element in 8 of them . thus 4 is the largest number in 8 subsets of s . the probability that 4 or 5 is the largest number is 24 / 32 = 3 / 4 . the answer is c ."
annotated_formula: divide(multiply(5, 4), power(const_2, 5))