Combined SAT Scores in the United States Could Be Approximated $T ( t ) = - 0.01774 t ^ { 3 } + 0.5928 t ^ { 2 } - 10.91 t + 1025$

Essay

Combined SAT scores in the United States could be approximated by
​ $T ( t ) = - 0.01774 t ^ { 3 } + 0.5928 t ^ { 2 } - 10.91 t + 1025$ ​
in the years 1964 - 1986. Here t is the number of years since 1964, and T is the combined SAT score average for the United States. Find all points of inflection of the graph of T, and interpret the result.
​
Enter your answers rounded to the nearest hundredth.