Natural Language Processing · TEE · papers
Q2b · Weather Naive Bayes
2025-02-21 · re-exam · recovered AI paper
Previous examination · complete worked answers
Question. Use the supplied class/conditional probabilities to predict Play Tennis for Outlook=Sunny, Temperature=Cool, Humidity=High, Windy=True. [10 marks]
Answer
Given
| Class | Prior | Sunny | Cool | High | True |
|---|---|---|---|---|---|
| Yes | 9/14 | 2/9 | 3/9 | 3/9 | 3/9 |
| No | 5/14 | 3/5 | 1/5 | 4/5 | 3/5 |
To find
Compare the Yes and No class scores.
Formula: which one and why
LaTeX: \mathrm{score}(c)=P(c)P(Sunny\mid c)P(Cool\mid c)P(High\mid c)P(True\mid c)Step 1. Multiply the Yes factors
9/14 × 2/9 × 3/9 × 3/9 × 3/9 = 1/189 = 0.005291005
Step 2. Multiply the No factors
5/14 × 3/5 × 1/5 × 4/5 × 3/5 = 18/875 = 0.020571429
Step 3. Compare and normalize
Yes=0.204582651, No=0.795417349
Final answer
Predict No. Apply the supplied categorical probabilities directly; adding vocabulary smoothing would solve a different problem.