Skip to content

Commit

Permalink
fixed formatting for 1I3
Browse files Browse the repository at this point in the history
  • Loading branch information
paul-laskowski committed Apr 30, 2024
1 parent 41fd471 commit e86cdb3
Showing 1 changed file with 7 additions and 6 deletions.
13 changes: 7 additions & 6 deletions _problems/unit-01/I-law-of-total-probability-and-Bayes-rule/3.md
Original file line number Diff line number Diff line change
Expand Up @@ -2,7 +2,8 @@
index: 3
level: 1
statement: |
A test for coronaviruses has the following properties: Given that a patient has the coronavirus, the conditional probability of a positive test is .95.
A test for coronaviruses has the following properties:
Given that a patient has the coronavirus, the conditional probability of a positive test is .95.
Given that a patient does not have the coronavirus, the conditional probability of a negative test is .95
You believe that in the population each patient has a .10 probability of having coronavirus.
What is the probability that a person has coronavirus, given they present a positive result?
Expand All @@ -11,13 +12,13 @@ Let $T$ be the event that a **t**est comes up positive. Let $C$ be the event th

The problem tells us that

- $$P(C) = 0.1$$
- $$P(T|C) = .95$$
- $$P(T^C|C^C) = .95$$
- $P(C) = 0.1$
- $P(T|C) = .95$
- $P(T^C|C^C) = .95$

First, by the complement rule, $$P(T|C^C) = 1 - P(T^C|C^C) = 1 - .95 = .05$$. Also by the complement rule, $$P(C^C) = 1-P(C) = 1 - 0.1 = 0.9$$
First, by the complement rule, $P(T|C^C) = 1 - P(T^C|C^C) = 1 - .95 = .05$. Also by the complement rule, $P(C^C) = 1-P(C) = 1 - 0.1 = 0.9$

To apply Bayes' Theorem, we first need the probability of a positive test. We notice that $$\{C, C^C\}$$ is a partition of the sample space. Writing the law of total probability,
To apply Bayes' Theorem, we first need the probability of a positive test. We notice that $\{C, C^C\}$ is a partition of the sample space. Writing the law of total probability,

$$P(T) = P(C)P(T|C) + P(C^C)P(T|C^C) = (0.1)(0.95) + (0.9)(0.05) = 0.14$$

Expand Down

0 comments on commit e86cdb3

Please sign in to comment.