[tex]b_{4} = \frac{1}{4} [/tex]
[tex]b_{6} = \frac{1}{6} [/tex]
[tex]{b_{5}}^{2} = b_{4} \times b_{6}[/tex]
[tex] {b_{5}}^{2} = \frac{1}{4} \times \frac{1}{6} = \frac{1}{24} [/tex]
[tex]b_{5} = \sqrt{ \frac{1}{24} } = \frac{1}{2 \sqrt{6} } = \frac{ \sqrt{6} }{12} [/tex]
