Answer
a. $49\%$, overestimates $1\%$
b. year $2020$
Work Step by Step
a. Given the formula $p=\frac{4x}{5}+25$ and year 2010 (thus $x=2010-1980=30$), we have $p=\frac{4(30)}{5}+25=49(\%)$. The bar graph gives a value of $48\%$; thus the model overestimates the data by $1\%$
b. Letting $p=57(\%)$, we have $\frac{4x}{5}+25=57$ or $\frac{4x}{5}=32$, which gives $x=40$ and it is corresponds to year $1980+40=2020$.
