Math
posted by Lisa on .
In 1990 the life expectancy of males in a certain country was 70.9 years. In 1994, it was 73.5 years. Let E represent the life expectancy in year t and let t represent the number of years since 1990. The liner function E(t) that fits the data is E(t)= _t+_ . Round to the nearest 10th.Use the function to predict life expectancy in 2009. E(19) = round to the nearest 10th

Life expectancy (E) increased (73.570.9)/4 = 0.65 years per year during that period.
If t=0 represents 1990, then
E = 70.9 + 0.65 t
Use that formula for E(19), and then do the rounding.
It is very unlikely that life expectancy will increase at that linear rate for 19 years, but that is what they are asking you to assume.