The numbers of polio cases in the world are shown in the table for various years Year Number of Polio Cases thousands 1988 1992 1996 2000 2005 2007 350 138 33 2 Find an equation of f Hint f t Let f t be the number of polio cases in thousands t years since 1980 3 2 1 3 Predict the number of polio cases in 2020 16 16 Round the coefficients to 4 decimal places Hint Predict in which year there will be 1 case of polio Hint