Answer
$\frac{1}{6}$
Work Step by Step
We know that $probability=\frac{\text{number of favourable outcomes}}{\text{number of all outcomes}}$
The total population (the number of all outcomes) is $174$
By using the table, the total number of people who have not completed four years of high school are the people who are in the less than 4 years category, which here is $29$
Hence the probability here is: $\frac{29}{174}=\frac{1}{6}$