Reverse conditional probability with a tree (tests and filters)

Question 1

30% of emails are spam. A filter flags 80% of spam emails and 10% of genuine emails. An email is flagged. What is the probability it is spam? Give 3 decimal places.

Answer 

Question 2

5% of people have a condition. A test is positive for 99% of people who have it and for 2% of people who don't. Someone tests positive. What is the probability they have the condition? Give 3 decimal places.

Answer 

Question 3

30% of emails are spam. A filter flags 80% of spam emails and 10% of genuine emails. An email is flagged. What is the probability it is spam? Give 3 decimal places.

Answer 

Question 4

2% of people have a condition. A test is positive for 95% of people who have it and for 10% of people who don't. Someone tests positive. What is the probability they have the condition? Give 3 decimal places.

Answer 

Question 5

30% of emails are spam. A filter flags 80% of spam emails and 10% of genuine emails. An email is flagged. What is the probability it is spam? Give 3 decimal places.

Answer 

Question 6

1% of people have a condition. A test is positive for 90% of people who have it and for 10% of people who don't. Someone tests positive. What is the probability they have the condition? Give 3 decimal places.

Answer 

Question 7

30% of emails are spam. A filter flags 90% of spam emails and 5% of genuine emails. An email is flagged. What is the probability it is spam? Give 3 decimal places.

Answer 

Question 8

1% of people have a condition. A test is positive for 95% of people who have it and for 2% of people who don't. Someone tests positive. What is the probability they have the condition? Give 3 decimal places.

Answer 

Question 9

30% of emails are spam. A filter flags 80% of spam emails and 5% of genuine emails. An email is flagged. What is the probability it is spam? Give 3 decimal places.

Answer 

Question 10

5% of people have a condition. A test is positive for 90% of people who have it and for 10% of people who don't. Someone tests positive. What is the probability they have the condition? Give 3 decimal places.

Answer 

Question 11

20% of emails are spam. A filter flags 80% of spam emails and 5% of genuine emails. An email is flagged. What is the probability it is spam? Give 3 decimal places.

Answer 

Question 12

10% of people have a condition. A test is positive for 99% of people who have it and for 10% of people who don't. Someone tests positive. What is the probability they have the condition? Give 3 decimal places.

Answer 

Question 13

30% of emails are spam. A filter flags 90% of spam emails and 10% of genuine emails. An email is flagged. What is the probability it is spam? Give 3 decimal places.

Answer 

Question 14

10% of people have a condition. A test is positive for 99% of people who have it and for 2% of people who don't. Someone tests positive. What is the probability they have the condition? Give 3 decimal places.

Answer 

Question 15

20% of emails are spam. A filter flags 80% of spam emails and 5% of genuine emails. An email is flagged. What is the probability it is spam? Give 3 decimal places.

Answer 

Question 16

5% of people have a condition. A test is positive for 99% of people who have it and for 10% of people who don't. Someone tests positive. What is the probability they have the condition? Give 3 decimal places.

Answer