Final answer:
A significant F ratio in ANOVA suggests that at least one mean differs significantly from others. It does not specify which means are different nor the variability among the groups, calling for further post hoc analysis to pinpoint specific differences.
Step-by-step explanation:
If the F ratio in ANOVA is significant, then a. at least one mean is significantly different than the other means. This result means that the variability among group means is more than would be expected by chance alone, indicating that at least one group mean is significantly different from the others. A significant F ratio does not imply that all means are different or that the variability between groups is less than the variability within groups.
It's important to note that ANOVA does not tell us which specific means are different from each other. If the ANOVA result is significant, we often proceed with post hoc tests, such as the Tukey's HSD (Honestly Significant Difference), to find out which specific group comparisons are significant.