The experimental bandhead excitation energies of two-quasineutron rotational bands in and nuclei have been used in the frame of the quantum Monte Carlo (QMC) pairing model to determine the strength G of the neutron pairing interaction. Using this strength, the bandhead excitation energies of two-quasineutron rotational bands in and have been predicted. Effects of the particle number fluctuation, introduced by the Bardeen-Cooper-Schrieffer approximation, and absent in the QMC approach, are discussed. Shapes and ground-state properties of neutron-rich zirconium and strontium isotopes are calculated using the macroscopic-microscopic method with the universal Woods-Saxon average potential and a monopole pairing residual interaction to obtain single-particle schemes relevant for pairing calculations. Our calculations are in good agreement with the experimental ground-state deformation.