$3)$ Measuring the track spacing on a CD

Reflecting the beam from a green $(532$nm wavelength$)$ laser pointer off a CD and onto a wall

$36$ inches away you note that the space between the central dot and the next closest dot is

~$13$ inches.

$1)$ What is the spacing between the tracks $($i$.$e$.,$ between the row of pits that contain the

data$)$ on the CD$?$ Use units of mm$.$

$2)$ Google to get the standard value of the track spacing distance in units of mm and

compare to the value you just calculated.