Answer:
60 questions
Explanation:
If the rate of the number of problems per minute is constant, we can write the following equation:
[tex]\frac{12\text{ problems}}{30\text{ minutes}}=\frac{x}{150\text{ minutes}}[/tex]Where x is the number of questions that she can answer in 150 minutes.
So, solving for x, we get:
[tex]\begin{gathered} \frac{12}{30}=\frac{x}{150} \\ \frac{12}{30}\times150=\frac{x}{150}\times150 \\ 60=x \end{gathered}[/tex]Therefore, Mary can expect to answer 60 questions in 150 minutes.