Let's first count the choices that include the number 1. If some three of the remaining numbers were 2, 3, and 4, then the conditions of the problem would be violated, because the denominators of all the fractions in the list are smaller than 2⋅3⋅4=24, and the product of the selected 5 numbers could not be 1. If instead of 2, 3, and 4 some other 3 integers are chosen, their product will be even larger, so the conditions of the problem cannot be met. The situation is similar if 3 fractions are chosen next to the number 1. Thus, in addition to the number 1, the choice must include 2 integers and 2 fractions, with the product of the integers equal to the product of the denominators of the fractions. There are exactly 21 ways to choose 2 integers in addition to the number 1, and the resulting products are in the following table:
We see that the numbers
12 and
24 appear in the table 2 times, the remaining numbers are unique. Thus, we get 21 options where the selected integers are the same as the denominators of the selected fractions, and in addition 4 options where the selected integers and the denominators of the selected fractions are not the same, but their product is either
12 or
24. In total, there are 25 options with the number
1.
Now we count the options that do not have the number 1. We have to choose either 3 integers and 2 fractions or 3 fractions and 2 integers. Since, due to symmetry, there are the same number of options of both types, we count the options involving 3 integers and 2 fractions. If 2 were not included in the selection, the product of the selected integers should be at least 3⋅4⋅5=60, but according to the multiplication table, the product of the denominators of any 2 fractions is less than 60, which is why the condition of the problem cannot be met. Therefore, 2 must be included in the selection. Similarly, we see that either 3 or 4 must also be included in the selection. We get the possibilities
2⋅3⋅4=24,2⋅3⋅5=30,2⋅3⋅6=36,2⋅3⋅7=42,2⋅3⋅8=48,2⋅4⋅5=40,2⋅4⋅6=48,2⋅4⋅7=56,2⋅4⋅8=64.
Of these 9 products, only 36 and 64 do not appear in the multiplication table above, the product 24 appears there 2 times and the remaining 6 products 1 time. So we get 2⋅0+1⋅2+6⋅1=8 possibilities. There are the same number of possibilities with 3 fractions and 2 integers. So there are 2⋅8=16 possibilities without the number 1.
Hence the total number of possibilities is 25+16=41.