Answer:
Δx = 6.33 x 10⁻³ m = 6.33 mm
Step-by-step explanation:
We can use the Young's Double Slit Experiment Formula here:

where,
Δx = distance between consecutive dark fringes = width of central bright fringe = ?
λ = wavelength of light = 633 nm = 6.33 x 10⁻⁷ m
L = distance between screen and slit = 3.7 m
d = slit width = 0.37 mm = 3.7 x 10⁻⁴ m
Therefore,

Δx = 6.33 x 10⁻³ m = 6.33 mm