Answer
a. $2.92x+236.0$
b. $309$ million.
c. same.
Work Step by Step
a. The total population is the sum of all Males and all Females; thus we have $T(x)=M(x)+F(x)=1.48x+115.1+1.44x+120.9=2.92x+236.0$
b. For year 2010, $x=2010-1985=25$, we have $T(x)=2.92(25)+236.0=309$ millions.
c. Reading from the bar graph, we have $T_1=152+157=309$ million; thus, the result from part-b is the same as in the bar graph.
