Find the fringewidth if the whole set up of the appartus is immersed in water of refractive index `mu - 4//3`

In Young's experiment fringe width is 2 mm for light of wavelength 6000 overset(@)(A) . Calculate the fringe width if the entire apparatus is immersed in water of refractive idex 4/3.

In Yong's double-slit experiment, the fringe width is 0.1 mm when light of wavelength 600 nm is used. Calculate the fringe width when the entire appartus is immersed in a medium of refractive index 4/3 by keeping the source of light in air.