Answer
a) \$39,000
b) \$38,843; this describes the estimate from part a accurately with a difference of only $157
c) \$38,648; this also describes the estimate from part a accurately with a difference of only \$352. However, the estimate from model 1 is more accurate.
Work Step by Step
a) Looking at the graph, what cost \$10,000 in 1967 would cost about \$39,000 in 1990. This is accurate since the point on the graph is just under the \$40,000 mark and definitely above the \$35,000 mark.
b) Since $x$ represents the number of years after 1980, plug 10 into $x$ to find the cost in 1990 of what cost \$10,000 in 1967. $C=1388(10)+24,963=38,843$
c) Since $x$ represents the number of years after 1980, plug 10 into $x$ to find the cost in 1990 of what cost \$10,000 in 1967. $C=3(10)2+1308(10)+25,268=38,648$
