Others have covered this amply already it's really not about hor far
light goes in 38us. However, I do want to plug one of my favorite
internet tools: The Google Calculator.

If you google on "38 microseconds * c in miles" it'll print out 7.079
for you. It does dimensional analysis and has a half decent library of
constants, too. By using 'in' at the end of the calculation you get to
specify what form you'd like to see your result.

-- dave j