Exponents and Logarithms

If. a. 4 marks The sound level of a telephone ringing is 80 dB. When the re alarm goes off, the ring of the telephone is not heard because the sound intensity of the re alarm is 12 times as intense as the sound intensity of the telephone. _1 = 10 10 The formula '2 is used to solve the question. In order to determine the sound level of the re alarm, Maren did the following calculations: i. Without looking at his work, how can we tell that Maren's answer of 69.2 dB can not be correct? ii. Explain where Maren made her mistake and provide a correct solution. b. 3 marks The 1960 earthquake in Chile measured 9.5 on the Richter scale. W, another earthquake in Chile registered 7.8 on the same Richter scale. In order to compare the m f=1o intensities, I, of these two earthquakes, the following formula can be used 10\" , where m and n are the Richter scale values of each of the earthquakes. How much more intense was the 1960 earthquake as compared to the 2005 earthquake? c. 3 marks Trinh has decided to save money to buy a new computer. She invests $800 in an account that earns 5% per year, compounded annually. Determine how long she needs to invest her money to have $1000. Do this graphically, provide the graph, the equations you use, the domain and range you used