We have a pipe that is closed at both ends, and we want to cut
it into three peices so that one pipe

We have a pipe that is closed at both ends, and we want to cut
it into three peices so that one pipe produces a frequency F1, the
second, F2 and the third, F3. The ratio of the three frequecies
F1:F2:F3 is 4:5:6, that is F2 = (5/4)F1 and F3=(6/4)F1 Keep in mind
that after cutting it into three peices, two of them would be
closed at end, and one of them would be open at both ends. What is
the length of each pipe? (there are multiple answers).