## Intermediate Algebra for College Students (7th Edition)

According to the formula, the percent of American adults who used smart phones to go online in $2013$ is 62%.
The calculated value underestimates the actual value by 1%. Consider $S=32+8.7x-0.3{{x}^{2}}$. Number of years from $2009$ to $2013$ = $4$years. So, put $x=4$in the given formula. $\Rightarrow S=32+8.7(4)-0.3{{(4)}^{2}}$ $\Rightarrow S=32+8.7\times 4-0.3\times 16$ $\Rightarrow S=32+34.8-4.8$ $\Rightarrow S=62\,%$ The actual percent shown in the bar graph is 63%, which is greater than the calculated value. Find the difference of both values. $=63percent-62percent\,\,=\,\,1percent$ So, the calculated value underestimates the actual value by 1%.