The loudest sound measured one night during a hockey game was 112 dB. The loudest sound measured during a hockey game the next night was 118 dB. What fraction of the sound intensity of the second game was the sound intensity of the first game?

[tex]\[ L = 10 \log \left( \frac{I}{I_0} \right) \][/tex]

Where:
[tex]\[ L \][/tex] = loudness in decibels
[tex]\[ I \][/tex] = sound intensity in watts per square meter [tex]\(\left(\frac{\text{watts}}{m^2}\right)\)[/tex]
[tex]\[ I_0 = 10^{-12} \text{ watts per square meter} \left(\frac{\text{watts}}{m^2}\right) \][/tex]

A. 0.25
B. 0.78
C. 0.95
D. 0.99



Answer :

Sure, let's solve this problem step by step.

1. Understand the given data:

- The loudness levels [tex]\( L_1 \)[/tex] and [tex]\( L_2 \)[/tex] for the two hockey games are 112 dB and 118 dB, respectively.
- The reference intensity [tex]\( I_0 = 10^{-12} \)[/tex] watts/m[tex]\(^2\)[/tex].

2. Convert loudness levels back to intensity:

The formula to relate loudness (in decibels) to intensity is:
[tex]\[ L = 10 \log_{10} \left( \frac{I}{I_0} \right) \][/tex]
Rearranging this formula to solve for [tex]\( I \)[/tex], we get:
[tex]\[ I = I_0 \cdot 10^{\frac{L}{10}} \][/tex]

Now we will use this formula to find the intensities [tex]\( I_1 \)[/tex] and [tex]\( I_2 \)[/tex].

- For the first game ([tex]\( L_1 = 112 \)[/tex] dB):
[tex]\[ I_1 = I_0 \cdot 10^{\frac{112}{10}} = 10^{-12} \cdot 10^{11.2} = 10^{-12 + 11.2} = 10^{-0.8} \][/tex]
This simplifies to:
[tex]\[ I_1 \approx 0.1584893192461111 \text{ watts/m}^2 \][/tex]

- For the second game ([tex]\( L_2 = 118 \)[/tex] dB):
[tex]\[ I_2 = I_0 \cdot 10^{\frac{118}{10}} = 10^{-12} \cdot 10^{11.8} = 10^{-12 + 11.8} = 10^{-0.2} \][/tex]
This simplifies to:
[tex]\[ I_2 \approx 0.6309573444801944 \text{ watts/m}^2 \][/tex]

3. Compute the fraction of the sound intensity of the first game to the second game:

The fraction of the intensities is given by:
[tex]\[ \text{Fraction} = \frac{I_1}{I_2} \][/tex]

Substituting the values of [tex]\( I_1 \)[/tex] and [tex]\( I_2 \)[/tex]:
[tex]\[ \text{Fraction} = \frac{0.1584893192461111}{0.6309573444801944} \approx 0.2511886431509572 \][/tex]

4. Conclusion:

The fraction of the sound intensity of the first game to the sound intensity of the second game is approximately [tex]\( 0.2512 \)[/tex], or 0.25 when rounded to two decimal places.

Therefore, the correct answer is:
[tex]\[ \boxed{0.25} \][/tex]