earthquake question involving logs

[Guest]

I need help with this question:

Sasha needs a muffler on her car. She has been told that the sound from her car was measured at 120 dB. After installing the new muffler, the loudness of her car is 75 dB. How many times more intense was the sound from her defective muffler?

so let I subscript A= one earthquake and I subscript B= the other earthquake

M= log ( I/ Isubscript 0)

I think the numbers 120 and 75 go on the bottom of the fraction?

M= log (I/120)
but then now what? and which varible am I solving for exactly? M or I?

thanks for the help in advance

 

[tkhunny]

Muffler noise is measured in Earthquakes?

 

[skeeter]

Muffler noise is measured in Earthquakes?

methinks there exists a bit of confusion regarding the Richter and decibel scales.
:shock:

 

[Guest]

haha oppsy ya I have no idea why I thought this was another earthquake question...anywho I must use the sound equation..ladeedada..you guys saw nothing.


- skips away ladeedada-