#### Answer

The probability that a randomly picked American has done less than 4 years of high school or 4 years of high school only is $\frac{85}{174}$.

#### Work Step by Step

We know that the probability that a randomly picked American has done less than 4 years of high school or 4 years of high school only is given below:
$\begin{align}
& P\left( \text{less than 4 years of high school} \right)=\frac{(\text{Numbers of students attend of high school less than 4 years)}}{(\text{Total numbers of students)}} \\
& =\frac{29}{174} \\
& P\left( \text{4 years of high school only} \right)=\frac{(\text{Numbers of students completed 4 years of high school)}}{(\text{Total numbers of students)}} \\
& =\frac{56}{174}
\end{align}$
$\begin{align}
& P\left( \text{less than 4 years of high school or 4 years of high school} \right)=\left[ P\left( \text{less than 4 years of high school} \right)+P\left( \text{4 years of high school only} \right) \right] \\
& =\frac{29}{174}+\frac{56}{\text{174}} \\
& =\frac{85}{174}
\end{align}$
Thus, the probability that a randomly picked American has done less than 4 years of high school or 4 years of high school only is $\frac{85}{174}$.