How do I solve this problem on decibels?

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Danielle


Manufacturers of a vacuum cleaner want to reduce its sound intensity to 22% of the original intensity. By how many decibels would the loudness be reduced?


Answer
The bel is defined as the logarithm of the sound intensity, relative to a standard intensity (the threshold of hearing). Ten decibels is one bel.
So an increase of 1 bel or 10 decibels is a 10^1-fold increase.

A 22% reduction means I(1) / I(2) = 0.78 (= 1.00 - 0.22)
log(0.78) = -0.109

A 22% decrease in sound intensity is a decrease of 0.109 bels = 1.09 decibels.

What do retail stores typically do with returned merchandise?




Crocoduck


I've returned a few items to retail stores that were defective when I bought them, such as a keyboard and a vacuum cleaner. Sometimes the boxes were not always in the same condition they were when the item was purchased. They don't even ask why you're returning it so they have no way of knowing if electronics are defective... do they test stuff out and put it back on the shelf? What happens if the box was damaged? Or do they just send all this stuff back to the manufacturers, and let the manufacturer figure out what to do with it?


Answer
They do a bonfire with it. It helps the disgruntled employees relieve some stress.




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