The life expectancy E , in years, for a child born years after 2000 is given by $E = 76.62 + 0.18 t$ In what birth year would a child have a life expectancy of 78.78 years?
A) 2014
B) 2012
C) 2010
D) That life expectancy never occurs.

Question

The life expectancy E , in years, for a child born  years after 2000 is given by $E = 76.62 + 0.18 t$ In what birth year would a child have a life expectancy of 78.78 years?
A) 2014 
B) 2012 
C) 2010 
D) That life expectancy never occurs.

Quizplus · Accepted Answer

Substitute 78.78 for E in the equation and solve for t:
$78.78 = 76.62 + 0.18t$
$2.16 = 0.18t$
$t = 12$
Therefore, a child born 12 years after 2000 would have a life expectancy of 78.78 years. 
Adding 12 years to 2000 gives 2012, so the answer is (B) 2012.

The Life Expectancy E , in Years, for a Child E=76.62+0.18tE = 76.62 + 0.18 tE=76.62+0.18t

The Life Expectancy E , in Years, for a Child $E = 76.62 + 0.18 t$