Let the mean-zero, Gaussian stress process \left\{X(t)\right\} be the sum of two very narrowband processes, such that \left\{X(t)\right\} has a bimodal autospectral density. For a specimen with m = 3 , compare the fatigue lives predicted by the Rayleigh approximation, the peak-approximation method, the single-moment method, the formula of Ortiz and Chen, and the formulas of Wirsching and Light.