For each of the 6 arrangements there are two changes that lead to a higher F ratio: swapping the 7 for the 9 (which gives an F of 2.08) and swapping the 8 for the 9 (wh...For each of the 6 arrangements there are two changes that lead to a higher F ratio: swapping the 7 for the 9 (which gives an F of 2.08) and swapping the 8 for the 9 (which gives an F of 2.07). Therefore, the number of arrangements with an F as large or larger than the actual arrangement is 6 (for the arrangements with the same F) + 12 (for the arrangements with a larger F), which makes 18 in all.