Foreign-born medical residents the percentage of

Question

Question: FOREIGN-BORN MEDICAL RESIDENTS The percentage of foreign-born residents in the United States from 1910 through 2000 is approximated by the function

P(t) = 0.04363t³ - 0.267t² - 1.59t + 14.7     (0 ≤ t ≤ 9)

Where t is measured in decades, with t 0 corresponding to 1910 . Show that the percentage of foreign-born residents was lowest in early 1970.