In a young's double slit experiment distance between slits is d=1...

In a young's double slit experiment distance between slits is $\mathrm{d}=1 \mathrm{~mm}$, Wavelength of light used is 600 nm and distance of screen from the plane of slits is $\mathrm{D}=1 \mathrm{~m}$. The minimum distance between two points on the screen where intensity falls to $75 \%$ of maximum intensity will be (Assume both sources of equal power).