The probability of a toothache, given evidence of a cavity, P(toothache |…
2021
The probability of a toothache, given evidence of a cavity, P(toothache | cavity) is __________.
- A.
0.400
- B.
0.600
- C.
0.280
- D.
0.216
Attempted by 49 students.
Show answer & explanation
Correct answer: B
Answer: 0.600
Explanation: The conditional probability P(toothache | cavity) is given directly by the model's conditional probability table (CPT). The CPT entry for toothache when a cavity is present is 0.600, meaning a 60% chance of a toothache given a cavity.
Definition: P(toothache | cavity) = P(toothache and cavity) / P(cavity).
In this question we read the conditional probability directly from the CPT: P(toothache | cavity) = 0.600.
Common pitfalls: 0.400 is the probability of no toothache given a cavity (1 − 0.600); do not confuse complements or joint probabilities with the conditional probability asked for here.