Lets consider a regression tree in which variance is 1.1065*e-10 and bias is 2.962e-13. Also the model RMSE on training set is 1.5e-5 and on training set is 1.2950e-5. Is the model is overfit or underfit. Actually i want to know that we know that a machine learning model perform well if it has low bias and low variance but what is margin between them.

Thank You.