#### Answer

The probability that a student is not from a high income family is $\frac{6}{7}$

#### Work Step by Step

We know that the total number of students is 350.
Therefore, $ n\left( S \right)=350$
Also, the number of students from a high income family is $50$
Therefore $ n\left( E \right)=50$
The probability of students from a high income family is given below:
$\begin{align}
& \text{P}\left( \text{high} \right)=\frac{\left( \begin{align}
& \text{Total number of students having } \\
& \text{ high income parents} \\
\end{align} \right)}{\text{Total number of students}} \\
& =\frac{50}{350} \\
& =\frac{1}{7}
\end{align}$
And the probability of students who are not from a high income family is given below,
$\begin{align}
& \text{P}\left( \text{not high} \right)=1-\text{P}\left( \text{high} \right) \\
& =1-\frac{1}{7} \\
& =\frac{6}{7}
\end{align}$
Thus, the probability that a student is not from a high income family is $\frac{6}{7}$.