\({\qquad \frac{\Delta t_{1}}{\Delta t_{2}}=\frac{P_{1}}{P_{2}} \times \frac{\sqrt{T_{2}}}{\sqrt{T_{1}}}} \)

\({\Rightarrow \quad \frac{6 \times 10^{-8}}{\Delta t_{2}}=(\sqrt{\frac{3}{5}}) \times 2} \)

\({\Rightarrow \quad \Delta t_{2}=6 \times 10^{-8} \times \frac{1}{2} \sqrt{\frac{5}{3}} \approx 4 \times 10^{-8} \text { sec }}\)