Help with this question?? AAMC test 2 spoilers

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giguerex35

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can somebody please explain why you have to do a "decimal log of the ratio" i thought a ratio was basically just a fraction which they do in the first part to get 20, which is why i put 50 because it is half. Help much appreciated and please be as thorough as possible

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No need to get bogged down in confusing terminology here. Start with the basics: dB = 10*log(I/I0). If you know an equation, it's probably easiest to start there. Here, it's useful to know that sound intensity is measured on a log scale.

Now, it's asking you the ratio of the minimum sound intensities heard by two different individuals. We're using "I" to represent intensity here. In other words, it's asking you for the ratio I(2)/I(1), where 1 and 2 denote the people. db for individual 1 = 20 dB and dB for individual 2 = 40. Solve for I(2)/I(1).

20 = 10*log(I(1)/I0)
40 = 10*log(I(2)/I0)

2 = log(I(1)/I0)
4 = log(I(2)/I0)

I don't like working in logs, so let's get rid of the logs:

10^2 = I(1)/I0
10^4 = I(2)/I0

Divide these by each other:

10^4/10^2 = [I(2)/I0]/[I(1)/I0]
10^2 = I(2)/I(1)

Therefore, the ratio of one to the other is 100:1 or 1:100.
 
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No need to get bogged down in confusing terminology here. Start with the basics: dB = 10*log(I/I0). If you know an equation, it's probably easiest to start there. Here, it's useful to know that sound intensity is measured on a log scale.

Now, it's asking you the ratio of the minimum sound intensities heard by two different individuals. We're using "I" to represent intensity here. In other words, it's asking you for the ratio I(2)/I(1), where 1 and 2 denote the people. db for individual 1 = 20 dB and dB for individual 2 = 40. Solve for I(2)/I(1).

20 = 10*log(I(1)/I0)
40 = 10*log(I(2)/I0)

2 = log(I(1)/I0)
4 = log(I(2)/I0)

I don't like working in logs, so let's get rid of the logs:

10^2 = I(1)/I0
10^4 = I(2)/I0

Divide these by each other:

10^4/10^2 = [I(2)/I0]/[I(1)/I0]
10^2 = I(2)/I(1)

Therefore, the ratio of one to the other is 100:1 or 1:100.
Much appreciated thanks
 
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