a) write model equation b) solution

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 75 years?

 

This is the full question

Answer 1

Life expectancy =y

 

Year =x

 

y= 55+0.2*x       required equation

 

75 =55+0.2*x

 

x= 20/0.2

  =100 birth year

 

 

Answer 2

Every 5 years the life expectancy increases 1 year. (5 x .2 = 1)

 

The difference in life expectancy is 75 - 55 = 20 years

 

Therefore it will take 5 x 20 = 100 years.

 

1900 + 100 = 2000