Module 6: Lesson 5

 

Self-Check 3

1. Question 13 on page 401 of the textbook
   13.  
       1. A possible method for arriving at the solution is as follows:
          
          
           
          
          
          

          Thus, the decibel level of the hairdryer is 70 dB.

       2. A possible method for arriving at the solution is shown (the equation that is used is the same as the one derived in “Example 4” on page 398 of the textbook). In this case, β1 will be the quieter noise and β2 will be the louder noise.
          
          
           
          
          
          Converting this equation to exponential form gives
          
          
           
          
          
          

          This means that the siren is approximately 1995 times louder than city traffic.

       3. A possible method for arriving at the solution is shown (the equation that is used is the same as the one derived in “Example 4” on page 398 of the textbook). Because the equation is shown explicitly in the textbook, it is not derived again here):
          
          
           
          
          
          Substituting what is known into the equation yields the following:
          
          
           
          
          
          

          Thus, the decibel level of the farm tractor is approximately 98 dB.

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