The ratio of resolving powers of an optical microscope for two wavelength $\lambda $1 = 4000 $\mathop A\limits^ \circ $ and ${\lambda _2}$ = 6000 $\mathop A\limits^ \circ $ is

Question

The ratio of resolving powers of an optical microscope for two wavelength $\lambda $₁ = 4000 $\mathop A\limits^ \circ $ and ${\lambda _2}$ = 6000 $\mathop A\limits^ \circ $ is

9 : 4