OpenIntro Chapter 2

Question 1

Which of the following is an example of two events that are disjoint?

Accepted Answer

Having a fever and having a normal body temperature

Question 2

Prevalence of 0.15: What is the probability that at least 1 of 3 have the disease?

Accepted Answer

0.386

Question 3

Consider two arbitrary events A and B, where P(A)=0.5 and P(B)=0.6. Can A and B be disjoint?

Accepted Answer

No

Question 4

You flip a fair coin 10 times and it lands H each time. The probability that it lands T next:

Accepted Answer

0.5

Question 5

30% of individuals have disease A, and 20% for disease B. The probability of having A or B is:

Accepted Answer

There is not enough information to answer this question.

Question 6

If you roll a fair die 5 times, what is the probability of rolling a 5 every time?

Accepted Answer

0.0001286

Question 7

If you roll a fair die 5 times, what is the probability of rolling at least one 5?

Accepted Answer

0.5981224

Question 8

If you roll a fair die a single time, what is the probability of rolling a 5?

Accepted Answer

1/6

Question 9

Prevalence of 0.15: what is the probability that 3 randomly selected people have the disease?

Accepted Answer

0.003375

Question 10

30% of individuals have disease A, and 20% for disease B. The probability of having neither is:

Accepted Answer

There is not enough information to answer this question.

Question 11

The following is true regarding disjoint vs. independent events (with positive probability):

Accepted Answer

If two events are disjoint, they CANNOT also be independent

Question 12

Prevalence of 0.15: what is the probability that none among 3 have the disease?

Accepted Answer

0.614125

Question 13

If you roll a fair 6-sided die, the probability of rolling an even number is:

Accepted Answer

0.5

Question 14

If you roll a fair die twice, what is the probability of rolling a 5 both times?

Accepted Answer

1/36

Question 15

30% of individuals have disease A, and 20% for disease B. The probability of having both is:

Accepted Answer

There is not enough information to answer this question.

Question 16

Suppose you roll two dice. Let A be the event that at least one die lands on 4. What is P(Ac)?

Accepted Answer

25/36

Questions 16