Ionic Equilibrium

The pH of a solution obtained by mixing 5 mL of $0.1 \mathrm{M} \mathrm{NH}_4 \mathrm{OH}$ solution with 250 mL of $0.1 \mathrm{M} \mathrm{NH}_4 \mathrm{Cl}$ solution is $\_\_\_\_$ $\times 10^{-2}$.(Nearest integer) Given: $\mathrm{pK}_{\mathrm{b}}\left(\mathrm{NH}_4 \mathrm{OH}\right)=4.74$

$$ \begin{aligned} & \log 2=0.30 \\ & \log 3=0.48 \\ & \log 5=0.70 \end{aligned} $$