Question

A country's population, in millions, is given by the exponential model P = 78.2e0.047t, where t represents years after 2000. After how many years will the country have a population of 210 million? (Round answer to the nearest tenth.)

Answer 1

$210= 78.2e^{0.047t} \implies 210/78.2 = e^{0.047t} \implies \\ \\ \ln (210/78.2 ) = 0.047t \implies t = \ln (210/78.2 )/0.047 \approx 21.0$



21.0 years