SOLUTION: I do not know how to solve this! Please someone show me step by step so I can understand!?!!??!?!??!? In 1992, life expectancy of males was 70.7 years. In 1996, it was 74.3 year

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Question 584368: I do not know how to solve this! Please someone show me step by step so I can understand!?!!??!?!??!?
In 1992, life expectancy of males was 70.7 years. In 1996, it was 74.3 years. Let E represent life expectancy in year t and let t represent the number of years since 1992.
The linear function E(t) that fits the data is
E(t) = ? t + ?
Use the function to predict life expectancy in males in 2007
E(15)= ?
Answer by KMST(5328) About Me  (Show Source):
You can put this solution on YOUR website!
Let's say the function is
E%28t%29=mt%2Bb and we want to find the numbers m abd b.
For the year 1992, t=0, because it is 0 years after 1992.
So E%280%29=m-0%2Bb=b=70.7 gives us highligth%28b=70.7%29
For 1996, t=4, because 1996 is 4 years after 1992, and the life expectancy of males is
E%284%29=m%2A4%2B70.7=74.3
That gives us the equation 4m%2B70.7=74.3
4m%2B70.7=74.3 --> 4m%2B70.7-70.7=74.3-70.7 --> 4m=3.6 -->
4m%2F4=3.6%2F4 --> highlight%28m=0.9%29
So the function is highlight%28E%28t%29=0.9t%2B70.7%29
For 2007, t=2007-1992=15. The life expectancy for males in 2007 can be predicted as
E%2815%29=0.9%2A15%2B70.7=13.5%2B70.7 --> highlight%28E%2815%29=84.2%29