\(\lambda=\frac{ V }{ f }=\frac{340}{340}=1\,m\)
First resonating length \(=\frac{\lambda}{4}=25\,cm\)
Second resonating length \(=\frac{3 \lambda}{4}=75\,cm\)
Third resonating length \(=\frac{5 \lambda}{4}=125\,cm\)
Height of water required \(=125-75=50\,cm\)
$ {z_1} = A\sin (kx - \omega \,t) $ , $ {z_2} = A\sin (kx + \omega \,t) $ , $ {z_3} = A\sin (ky - \omega \,t) $ .