[tex]Formula: \ M_{pr}=M_g= \sqrt{x \cdot y} \\ x= \frac{245}{27} ; \ y= \frac{243}{80} ; \\ M_{pr}= \sqrt{ \frac{245}{27} \cdot \frac{243}{80} } = \sqrt{ \frac{49}{1}\cdot \frac{9}{16} } = \sqrt{ \frac{9}{1} } \cdot \sqrt{ \frac{9}{16} } = \sqrt{9} \cdot \frac{ \sqrt{9} }{ \sqrt{16} } =3 \cdot \frac{3}{4} =\boxed{ \frac{9}{4} }.[/tex]
