The number of pages Cameron reads varies directly with time in minutes. He can read 15 pages in 60 minutes. What is the constant of proportionality for the number of minutes to read 1 page.
We can set up the proportion $\frac{15\text{ pages}}{60\text{ minutes}} = \frac{1\text{ page}}{x\text{ minutes}}$ where $x$ is the number of minutes to read 1 page. Cross-multiplying gives $15x = 60\cdot 1$ or $x = 4$. Thus, the constant of proportionality is $\boxed{4}$.
