Common Core HSS.CP.B.6 worksheet

Question 1

1% of people have a condition. A test is positive for 95% of people who have it and for 5% of people who don't. Someone tests positive. What is the probability they have the condition? Give 3 decimal places.

Answer 

Question 2

P(B) = 0.2 and P(A and B) = 0.1. Find P(A | B).

Answer 

Question 3

Phone survey: Android: under 18 20, 18+ 21 iPhone: under 18 11, 18+ 25 A person aged 18+ is chosen at random. Find P(iPhone | 18+) as a fraction in simplest form.

Answer (as a fraction)

Question 4

P(A) = 0.6, P(B) = 0.5 and P(A and B) = 0.3. Are A and B independent?

• A. Yes
• B. No

Question 5

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 6

Survey: Likes science & is in Club — 16; Likes science & not in Club — 12; Doesn't like science & in Club — 24; neither — 21. Given a student is in the Club, what is the probability they like science? Simplest form.

Answer (as a fraction)

Question 7

The probability it rains tomorrow is 0.5. If it rains, the probability the bus is late is 0.8. What is the probability that it rains and the bus is late?

Answer 

Question 8

1% 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 9

P(B) = 0.4 and P(A and B) = 0.08. Find P(A | B).

Answer 

Question 10

Phone survey: Android: under 18 33, 18+ 25 iPhone: under 18 29, 18+ 16 A person aged 18+ is chosen at random. Find P(iPhone | 18+) as a fraction in simplest form.

Answer (as a fraction)

Question 11

P(A) = 0.6, P(B) = 0.5 and P(A and B) = 0.3. Are A and B independent?

• A. Yes
• B. No

Question 12

20% 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 13

Survey: Likes science & is in Club — 6; Likes science & not in Club — 15; Doesn't like science & in Club — 17; neither — 25. Given a student is in the Club, what is the probability they like science? Simplest form.

Answer (as a fraction)

Question 14

The probability it rains tomorrow is 0.5. If it rains, the probability the bus is late is 0.8. What is the probability that it rains and the bus is late?

Answer 

Question 15

1% of people have a condition. A test is positive for 90% 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 16

P(B) = 0.2 and P(A and B) = 0.15. Find P(A | B).

Answer