
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.
y =0.189x +70.8
x = (y70.8)/0.189
when y = 80.2
x = (80.270.8)/0.189 = 9.4/0.189 = 49.73
hence required year is 1970 +49.73 = 2019.73 = 2019
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