Using a calculator, $\sqrt{15} \approx 3.87$ and $\sqrt{50} \approx 7.07$. The integers between these real numbers are $4,5,6,7$, of which there are 4 . Alternatively, we could note that integers between $\sqrt{15}$ and $\sqrt{50}$ correspond to values of $\sqrt{n}$ where $n$ is a perfect square and $n$ is between 15 and 50 . The perfect squares between 15 and 50 are $16,25,36,49$, of which there are 4.