Answer
The probability that a randomly picked American has done 4 years of high school only or less than 4 years of college is $\frac{50}{87}$.
Work Step by Step
We know that the probability that a randomly picked American has done 4 years of high school only or less than 4 years of college given below:
$\begin{align}
& P\left( \text{completed 4 years of high school} \right)=\frac{(\text{Numbers of students completed 4 years of high school)}}{(\text{Total numbers of students)}} \\
& =\frac{56}{174} \\
& P\left( \text{less than 4 years college} \right)=\frac{(\text{Numbers of students who attend less than 4 years college)}}{(\text{Total numbers of students)}} \\
& =\frac{44}{174}
\end{align}$
$\begin{align}
& P\left( \text{4 years of high school or less than 4 years college} \right)=\left[ P\left( \text{completed 4 years of high school} \right)+P\left( \text{less than 4 years college} \right) \right] \\
& =\frac{56}{\text{174}}+\frac{44}{174} \\
& =\frac{100}{174} \\
& =\frac{50}{87}
\end{align}$
Thus, the probability that a randomly picked American has done 4 years of high school only or less than 4 years of college is $\frac{50}{87}$.
