7. The work of an epidemiologist is to investigate the root cause of a disease and determine the strategy to control or even stop the spread of the disease. An outbreak was caused by disease Y and an epidemiologist was asked to investigate it. When the disease Y was firstly identified in January 2015, the initial number of people infected by the disease Y was 140. Data from the infected people were collected monthly by the epidemiologist to observe the trend of the disease. Based on the collected data, the epidemiologist found out that there was a consistent increment in the number of patients infected, 1.5% as compared to the previous month. By having Po to represent the initial patients infected by the disease in January 2015, P. represents the number of patients infected by the disease for n months since January 2015. a. Calculate the total number of infected patients in February, March, April, and May 2015 in terms of the variables n and Po. b. Based on the answer obtained from 6a, determine a linear recurrence relation to describe the increment of water level after n years. c. An emergency plan will be triggered to increase the preparedness of the hospital in handling the outbreak if the number of infected patients exceeds 300. How many months after January 2015 that the emergency plan will be triggered if the trend of infection rate follows the sequence?