Question 972982
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Sound varies with the inverse of the square of the distance. A distance three times farther yields: 
{{{intensity=1/(3^2)}}}
{{{intensity=1/9}}}
The intensity at the new distance is 1/9 the original intensity.
The given answers make no sense. Once you decrease an amount 1 time, nothing is left. I think the intended answer is D, but this, too, is wrong. If we take a quantity, say 1, and take nine times it we get 9. Now if we decrease the original 1 by nine times 1 we have 1-0=-8. So even answer D would imply after making the distance three times greater the sound intensity is -8 (if the original intensity is considered as 1). In general, the phrases "three times as low", "three times smaller", or "three times less" have no meaning.