This exercise uses the population growth model. The bat population in a certain Midwestern county was 220,000 in 2012, and the observed doubling time for the population is 28 years. (a) Find an exponential model n(t) = no2t/2 for the population t years after 2012. n(t) = 220000 - 2 28 (b) Find an exponential model m(t) = ngert for the population & years after 2012. (Round your / value to four decimal places.) n(t) = 220000 - e-0247: (c) Sketch a graph of the population at time t. n(t) n(t) 1400000 1400000 1200000 1200000 1000000 1000000 800000 800000 600000 600000 400000 400000 200000 200000 10 20 30 40 50 60 O 10 20 30 40 50 60 n(t) n(t) 1400000 1400000 1200000 1200000 1000000 1000000 800000 800000 600000 600000 400000 400000 200000 200000 10 20 30 40 50 60 10 20 30 40 O 50 60 (d) Estimate how long it takes the population to reach 2 million. (Round your answer to two decimal places.) 8.90 X yr