The number of incarcerated adults N (measured in thousands) in a certain country can be approximated by the equation Upper N equals negative 4.7 x squared plus 71.9 x plus 1900 , where x is the number of years since 2000. In 2007 , the number of incarcerated adults peaked. How many adults were incarcerated in that year?The number of inmates N (measured in thousands) in federal and state prisons can be approximated by the equation Upper N equals negative 2.02 x squared plus 77.88 x plus 745 , where x is the number of years since 1990. In what year was the number of inmates expected to be 1 comma 388 comma 680 ?