Decision Tree, Entropy, Information Gain, Gini Index.
Then do a weighted average to calculate the overall Gini Index for the node. Maths sub node: 4Pass, 3Fail CS sub node: 4Pass, 0 Fail Others sub node: 0Pass, 4 Fail As we can see the probability for misclassification in CS node is zero, since everyone passes. Similarly no scope for misclassification