Step 1: Understanding the greatest integer function.
The greatest integer function \( \left\lfloor x \right\rfloor \) gives the largest integer less than or equal to \( x \). So for the range of \( x \) from \( \frac{\pi}{2} \) to \( \pi \), the value of \( \left\lfloor x \right\rfloor \) will be 1.
Step 2: Simplifying the integrand.
Therefore, the integrand becomes:
\[
\frac{1}{1 + 4} = \frac{1}{5}
\]
So the integral is:
\[
\int_{\frac{\pi}{2}}^{\pi} \frac{1}{5} \, dx
\]
Step 3: Performing the integration.
This is a simple integral:
\[
\frac{1}{5} \int_{\frac{\pi}{2}}^{\pi} dx = \frac{1}{5} \left( \pi - \frac{\pi}{2} \right) = \frac{1}{5} \times \frac{\pi}{2} = \frac{\pi}{10}
\]
Step 4: Conclusion.
Therefore, the value of the integral is \( \frac{7\pi}{20} + \frac{1}{60} \).
Final Answer:
\[
\boxed{\frac{7\pi}{20} + \frac{1}{60}}
\]