\(\mathrm{pH} =7+\frac{1}{2} \mathrm{p} K_{\mathrm{a}}-\frac{1}{2} \mathrm{p} K_{\mathrm{b}} \)
\(=7+\frac{1}{2}(3.2)-\frac{1}{2}(3.4) \)
\(=6.9\)