Question 35806
Intensity of light, measured in lux(lx) varies inversely as the square of the distance between the light source and the object illuminated. 
A light hangs 4.8 feet above the center of a circular table 7.2 feet in diameter. If the illumination is 25 lux at the center of the table, what is the illumination at the edge of the table?

I=k/d^2
25=k/4.8^2
k=576
Equation:
I=576/d^2
Find distance from light to edge of table.
Use Pytagoras: 4.8^2 + 3.6^2 = d^2
d^2=36
Intensity = 576/36= 16 lumins
Cheers,
Stan H.