In 1994, the life expectancy of males in a certain country was 67.8 years. In 2000, it was 70.6 years. Let E represent the life expectancy in year t and let t represent the number of years since 1994. The linear function
E(t)that fits the data is E(t)=__t+__ round to nearest tenth. Use the function to predict life expectancy of males in 2005. E(t)=__. Round to the nearest 10.
Since E = 67.8 when t is zero,
E(t) = 67.8 + a t
Using data from 2000 (when t = 6),
70.6 = 67.8 + 6 a
6a = 2.8, so
a = 0.47
In 2005, t = 11
so E in 2005 = 67.8 + 0.47*11 = 73.0
Such a linear relationship cannot be expected to be valid many years beyond 2000. It is called an extrapolation.