A certain country's Gross Domestic product (in millions of dollars) t years since the beginning of 1997 is given by
G(t)= -2.4t^3 + 48t^2 + 18t + 8000
for o<t<12 . Determine the year that GDP is growing at a rate of at least $275 000 000 per year.Also,determine whether or not the growth rate of GDP drops back below that rate of growth, if so,the year that it happens.