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The Problem

The number of years a person born in the United States is expected to livecan be apporximated by the equation y=0.189x+70.8, where x is the number of years since 1970. Solve this equation for x. Use this new equation to determine in which year the apporximate life expectancy will be 80.2 years.

Answer provided by our tutors

y =0.189x +70.8

x = (y-70.8)/0.189

when y = 80.2

 x = (80.2-70.8)/0.189 = 9.4/0.189 = 49.73

 hence required year is 1970 +49.73 = 2019.73 = 2019

 

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