In 1995, the life expectancy of males in a certain country was 69.8 years. In 1999, it was 73.6 years. Let E represent the life expectancy in year t and let t represent the number the number of years since 1995.
The linear function E(t) that fits the data is
E(t) = ? t + ?
Use the function to predict the life expectancy of males in 2005.
E (10) = ?
Solution:-
According to equation
In 1995 t=0
Suppose equation is E(t)=at+b
Put t=0 and E(t)=69.8
69.8=a*0+b
b=69.8
in 1999 E(t)=73.6
73.6=a*4+b
Put all values
73.6=4x+69.8
4x=3.8
X=
X=0.95
So the equation is
E(t)=0.95t+69.8
For year 2005 t=10
E(10)=0.95*10+69.8
E(10)=9.5+69.8
E(10)=79.3