Question 1120409
<br>
Solving the problem as the other tutor did, using the formal definition of inverse proportion to find the constant of proportionality, is of course a valid method.<br>
And you should be able to use that method, as it may be required in a more complicated problem.<br>
But for a simple problem like this, I personally find it far easier simply to say that since the distance is multiplied by 3, the intensity is multiplied by 1/(3^2) = 1/9.<br>
Then 1/9 of 3 foot-candles is 1/3 foot-candle, answer B.