[tex] T = 2\pi \sqrt{\dfrac{L}{32}} [/tex]
[tex] \dfrac{T}{2\pi} = \sqrt{\dfrac{L}{32}} [/tex]
[tex]L = \dfrac{32 T^2}{4\pi^2} = \dfrac{8T^2}{\pi^2} [/tex]
[tex]L = \dfrac{32 (2.2)^2}{4(3.14)^2} =3.927 \textrm{ feet}[/tex]
Second choice: 4 feet
