Final answer:
If the plot of the residuals is cone shaped, this violates the assumption that the residual errors are mutually independent.
Step-by-step explanation:
If the plot of the residuals is cone shaped, this violates the assumption that the residual errors are mutually independent. Residuals are the differences between the observed values and the predicted values from a regression line. When the plot of the residuals forms a cone shape, it suggests that there is a pattern or correlation between the residuals, indicating that the errors are not independent.