\(\frac{\lambda_{\mathrm{B}}}{\lambda_{\mathrm{G}}}=\frac{\mathrm{P}_{\mathrm{G}}}{\mathrm{P}_{\mathrm{B}}}=\frac{\mathrm{mv}_{\mathrm{G}}}{\mathrm{mv}_{\mathrm{B}}}\)
Speed of electron \(v \propto \frac{z}{n}\)
so \(\frac{\lambda_{B}}{\lambda_{G}}=\frac{n_{B}}{n_{G}}=\frac{3}{1} \Rightarrow \lambda_{B}=3 \lambda_{G}\)