Two parallel narrow slits are at a distance of 0.840 mm apart. Each of them has a width of 0.140 mm. The double slit is illuminated with parallel light of wavelength 546.1 nm.

(a) Find the ratio of the intensity of the central maximum to that of its adjacent maximum. (1 : 0.912)
(b) Certain interference maxima are missing. Find the position of the missing maximum that is nearest to the central maximum. (13.41' from central maximum)