Answer
$L=30m$
Work Step by Step
We are given all of the information needed to find the farthest distance a person can be from the wall, L, using equation (36-17).
$L=\frac{Dd}{1.22 \lambda}$
where D is the diameter of the holes, d is the diameter of the person's pupils, and lambda is the wavelength.
$L=\frac{Dd}{1.22 \lambda}$
$L=\frac{5.0*10^{-3}*4.0*10^{-3}}{1.22 550*10^{-9}}$
$L=30m$
