Combined SAT Scores in the United States Could Be Approximated

Multiple Choice

Combined SAT scores in the United States could be approximated by in the years 1968 - 1988. Here t is the number of years since 1968, 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.

A) (20, 904.12)
B) (18.71, 903.81)
C) (0, 0)
D) (15.85, 903.33) , (21.58, 904.30)
E) (0, 0) , (20, 904.12)