- CFA Exams
- CFA Level I Exam
- Topic 1. Quantitative Methods
- Learning Module 3. Probability Concepts
- Subject 3. Addition Rule for Probabilities: the Probability that at Least One of Two Events Will Occur
CFA Practice Question
Roll a die and flip a coin, P(5 OR heads) = ______.
B. 1/12
C. 7/12
A. 5/12
B. 1/12
C. 7/12
Correct Answer: C
P(5 or heads) = P(5) + P(heads) - P(5 and heads) = 7/12
P(5) = 1/6, P(heads) = 1/2, P(A and heads) = 1/6 x 1/2 = 1/12
P(5 or heads) = P(5) + P(heads) - P(5 and heads) = 7/12
User Contributed Comments 6
| User | Comment |
|---|---|
| eejo | 1/6 + 1/2 -1/12= 2/12 + 6/12 - 1/12= 8/12-1/12= 7/12 |
| morek | why are these not mutually exclusive? |
| Vikku | morek, bcoz they are independent events. A 5 & a head, both can happen together. |
| olagbami | @ morek....p(5 and head) is greater than zero, so they are both mutually exclusive events. |
| khalifa92 | mutually exclusive not- |
| Mheaton37 | Heads is a 50% chance, adding another event on top of that with "or" would mean 5/12 and 1/12 are automatically eliminated as answers. |