Posted by **Jessie** on Saturday, May 7, 2011 at 2:12am.

in 1991 the life expectancy of males in certain county was 68.6 years in 1996 it was 70.9 years let t represent the life expectancy in year t and let t represent the number of years since 1991

- Math 116 -
**bobpursley**, Saturday, May 7, 2011 at 4:54am
I know that model

life expectance= slope*time + constant is the math model here.

first thing, slope:

slope= changelifeexpatance/changetime

= (70.9-68.6)/(1996-1991)=2.3/5

life expectance= 2.3/5 * year + constant

now to find the constant:

life expectancey= 2.3/5 *t + constant where t= (year-1991)

70.9=2.3/5* 5 + constant

solving for constant,

70.9=2.3 + constant

constant= 70.9-2.3=68.6

amazing, so now you have

lifeexpectancey=2.3/5 * t+68.6 where t is the years since 1991

- Math 116 -
**Jessie**, Saturday, May 7, 2011 at 2:12pm
thank u

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