Question 188386: The average life expectancy 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 expectancy be 91 years?
I think the answer is 2080. I just don't know how to show this in algebraic terms.
Answer by stanbon(75887)   (Show Source):
You can put this solution on YOUR website! The average life expectancy for American men born in 1900 was 55 years. Life expectancy has increased by about 0.2 year for each birth year after 1900. ------------------
You have one point (0,55) and a slope (0.2).
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The "0" represents 1990
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The equation form is "life expectancy" = 0.2(years after 1990) + 55
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E(x) = 0.2x + 55 , where x is the number of years after 1990.
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If this trend continues for which birth year will the average life expectancy be 91 years?
91 = 0.2x + 55
0.2x = 36
x = 180
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Year = 1990 + 180 = 2170
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Cheers,
Stan H.
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