Problema Solution
In 1994, the life expectancy of males in a certain country was 72.2 years. In 1998, it was 76.1. Let E represent the life expectancy in year t and let t represent the number of years since 1994.
The linear function E(t) that fit the data is
E(t) = __t +___ (round to the nearest tenth)
Use the function to predict the life expectancy of males in 2003.
E(9) = ____ (round to the nearest tenth)
Answer provided by our tutors
E(t) = a*t + b,
where a and b are the constants that we need to find
since E(0) = 72.2 we have
a*0 + b = 72.2
b = 72.2
since E(4) = 76.1 we have
4a + b = 76.1
4a + 72.2 = 76.1
4a = 76.1 - 72.2
4a = 3.9
a = 3.9/4
a = 0.975
The linear function E(t) that fit the data is
E(t) = 0.98t + 72.2 (round to the nearest tenth)
for the year of 2003 we have t = 2003 - 1994 = 9
E(9) = 0.98*9 + 72.2
E(9) = 81