Answer:
Step-by-step explanation:
This is a problem based on interference pf light waves.
wavelength of light λ = 553 nm 
slit separation d = .134 x 10⁻³ m 
screen distance D = 4.5 m 
for fourth order bright fringe, path- length difference = 4 x λ 
= 4 x 553 
= 2212 nm . 
= 2.212 μm