Question

According to one mathematical model, the average life expenctancy for American men born in 1900 was 55 years. Life expectancy has increased by about 0.2 year for each birth year after 1900. If this trend continues, for which birth year will the average life expentancy be 73 years?

Answer 1

If this trend continues, life expectancy will be 73 years in the year 1990

Explanation:

Hi

first of all, we build a model with the knowns of the problem, so we have
`LifeExpectancy=LE(x)=55+0.2x, x` in years after 1900, then we have

`73=55+0.2x` as we isolate for
`x`,
`x=(73-55)/(0.2)=90`, finally, we obtain that the birth year which the average life expectancy will be 73 years is 1990