A biochemist prepares a buffer solution using a weak acid with $K_a = 1.0 \times 10^{-5}$ ($pK_a = 5$). According to the Henderson-Hasselbalch equation $\text{pH} = pK_a + \log_{10}\left(\frac{[\text{A}^-]}{[\text{HA}]}\right)$, if the ratio of conjugate base $[\text{A}^-]$ to weak acid $[\text{HA}]$ is $40:1$, what is the pH of the solution? (Use $\log_{10}(2) \approx 0.301$)