Question

The intensity (I) of light received at a source varies inversely as the square of the distance (d) from the source. If the light intensity is 98 foot-candles at 27 feet, find the light intensity at 9 feet.

Answer 1

\[I = \frac{k}{d^2}\]

\[98 = \frac{k}{27^2}\]

k = 71442

Answer 2

\[I = \frac{71442}{9}\]

I = 7938

Answer 3

The correct answer was 882?? Oh man I hate these problems!!

Answer 4

saifoo is correct in the set up
just forgot to square the 9
71442/81 = 882

Answer 5

Ohhh!
SORRYY!