According to data from the U. S. Census Bureau for the period 2000–2007, the number of male students enrolled in high school in the United States can be approximated by the function m(x) = −0.002x^3 +0.02x 2 +0.039x +6.11 where x is the number of years since 2000 and m(x) is the number of male students in millions. The number of female students enrolled in high school in the United States can be approximated by the function m(x) = −0.004x 3 +0.019x^2 +0.145x +5.78 where x is the number of years since 2000 and m(x) is the number of female students in millions. Estimate the total number of students enrolled in high school in the United States in 2007.