4.3

MATH 115 — Chapter 4.3 Flashcards

1. Q: What does P(B|A) mean?
A: Probability of B, given that A occurred.

2. Q: What is the complement rule?
A: P(not A) = 1 - P(A)

3. Q: What is a false negative?
A: Negative result when the condition is present.

4. Q: How do you find at least one success in n independent trials?
A: P(at least one) = 1 - (1 - p)^n

5. Q: What is a prior probability?
A: An initial probability before new information.

6. Q: What does the vertical bar | mean?
A: Given that.

7. Q: What is Bayes' theorem?
A: P(A|B) = [P(B|A) * P(A)] / P(B)

8. Q: What does a probability of 0 mean?
A: The event is impossible.

9. Q: What is prevalence?
A: The proportion of a population with a condition.

10. Q: How do you find P(A|B) from a table?
A: Count A and B together / total count for B.

11. Q: What does "at least one" mean?
A: One or more occurrences.

12. Q: What is confusion of the inverse?
A: Incorrectly assuming P(A|B) = P(B|A).

13. Q: What is a true positive?
A: Positive result when the condition is present.

14. Q: What is the formula for conditional probability?
A: P(B|A) = P(A and B) / P(A)

15. Q: What is a posterior probability?
A: A probability revised using new information.

16. Q: What does P(A and B) mean?
A: Probability that both A and B occur.

17. Q: How do you find the probability of no occurrences in n trials?
A: P(none) = (1 - p)^n

18. Q: When do you use Bayes' theorem?
A: To revise a probability using new information.

19. Q: What is conditional probability?
A: Probability calculated with additional information.

20. Q: What is the complement of at least one occurrence?
A: No occurrences.

21. Q: What does a probability of 1 mean?
A: The event is certain to occur.

22. Q: What does P(A) mean in P(B|A)?
A: Probability of the given event A.

23. Q: What is a true negative?
A: Negative result when the condition is absent.

24. Q: Why use the complement rule for at least one?
A: Finding the probability of zero occurrences is often easier.

25. Q: Does P(A|B) generally equal P(B|A)?
A: No, conditional probabilities are generally not equal.

26. Q: What is the formula for at least one occurrence?
A: P(at least one) = 1 - P(none)

27. Q: What is a false positive?
A: Positive result when the condition is absent.

28. Q: What is the difference between prior and posterior probability?
A: Prior is initial; posterior uses additional information.

29. Q: What does P(B) mean in Bayes' theorem?
A: The overall probability of B.

30. Q: What should you assume when finding P(B|A) intuitively?
A: Assume event A has already occurred.

31. Q: How do you use conditional probability with a two-way table?
A: Restrict to the given event's row or column, then divide.

32. Q: What does P(B|A) represent in words?
A: The chance of B after knowing A occurred.

33. Q: What does the complement of A mean?
A: Event A does not occur.

34. Q: What is the main idea of conditional probability?
A: Calculate a probability using information about another event.

35. Q: What does P(B|A) equal in terms of joint probability?
A: P(A and B) / P(A)