The population of a certain region grew from 18.3 million in 2005 to 23.3 million in 2012. a. Find a function of the form P(t)= Ce^kt that models the population growth of the region. Here, t is the number of years since 2005 , and P(t) is in millions. Round your k value to 3 decimal places. P(t)= b. Use your model to predict the population of this region in 2019. Round your answer to the nearest tenth of a million.