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