The null hypothesis for this ANOVA F test is: the population mean load failures for the three etch times are all different the population mean load failure is lowest for the 15‑second condition and highest for 60‑second condition at least one population mean load failure differs the sample mean load failure is lowest for the 15‑second condition and highest for 60‑second condition the sample mean load failures for the three etch times are all different the population mean load failures for the three etch times are all equal