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a. Suppose events \(E\) and \(F\) are mutually exclusive with \(P(E)=0.41\) and \(P(E)=0.23\). i. What is the value of \(P(E \cap F) ?\) ii. What is the value of \(P(E \cup F) ?\) b. Suppose that for events \(A\) and \(B, P(A)=0.26, P(B)=0.34\), and \(P(A \cup B)=0.47\). Are \(A\) and \(B\) mutually exclusive? How can you tell?

Short Answer

Expert verified
a. i. Since events E and F are mutually exclusive, \(P(E \cap F) = 0\). a. ii. For mutually exclusive events E and F, \(P(E \cup F) = P(E) + P(F) = 0.41 + 0.23 = 0.64\). b. We find that \(P(A \cap B) = 0.13\). Since this is not equal to 0, events A and B are not mutually exclusive.

Step by step solution

01

i. Finding the value of \(P(E \cap F)\) for mutually exclusive events

Since events E and F are mutually exclusive, by definition, they cannot occur simultaneously. This means that the probability of their intersection, \(P(E \cap F)\), must be equal to 0.
02

ii. Finding the value of \(P(E \cup F)\) for mutually exclusive events

To find the probability of the union of these two mutually exclusive events, we can simply add their individual probabilities, as they cannot occur at the same time. Thus, we have: \(P(E \cup F) = P(E) + P(F) = 0.41 + 0.23 = 0.64\). So the value of \(P(E \cup F)\) is 0.64. #Part b: Determining if events A and B are mutually exclusive#
03

i. Computing the probability of the intersection of events A and B

We are given the probabilities of events A, B and their union, and we'll use these values to determine if A and B are mutually exclusive. First, we need to compute the value of \(P(A \cap B)\). We can use the following formula that relates probabilities of the union and intersection of two events: \(P(A \cup B) = P(A) + P(B) - P(A \cap B)\) Plugging in the given values, we get: \(0.47 = 0.26 + 0.34 - P(A \cap B)\) Now we can solve for \(P(A \cap B)\: \(P(A \cap B) = 0.26 + 0.34 - 0.47 = 0.13\)
04

ii. Determining if events A and B are mutually exclusive

Now that we have found the probability of the intersection of events A and B, we can determine if they are mutually exclusive. If events A and B were mutually exclusive, their intersection probability would be 0. However, we found that \(P(A \cap B) = 0.13\), which is not equal to 0. Therefore, events A and B are not mutually exclusive.

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Mutually Exclusive Events
When we refer to events as \textbf{mutually exclusive}, we mean that these events cannot happen at the same time. For example, when flipping a regular coin, the events 'landing on heads' and 'landing on tails' are mutually exclusive because the coin can only land on one side at a time.

In probability terms, if events are mutually exclusive, the probability of their intersection, denoted as \( P(E \cap F) \), is always zero because there's no scenario in which both events can take place simultaneously. Hence, if \( E \) and \( F \) are mutually exclusive and we know \( P(E) = 0.41 \) and \( P(F) = 0.23 \), then \( P(E \cap F) = 0 \). This concept is crucial to understanding how probable outcomes are determined in scenarios where certain results are exclusive to each other.
Probability Intersection
The \textbf{probability intersection} refers to the probability that two events, \( E \) and \( F \), both occur. It is denoted by \( P(E \cap F) \). To visualize this, think of a Venn diagram with two overlapping circles, where each circle represents an event, and their overlap indicates the intersection.

For mutually exclusive events, as we already know, this intersection probability is zero. However, if two events can occur together, then we calculate the intersection probability by determining how likely it is that both events happen simultaneously. For instance, if you have a bag of red and blue marbles, and events \( A \) and \( B \) represent drawing a red marble and a blue marble, then the probability of drawing both at the same time (without replacement) can be calculated by determining the overlap in those events.
Probability Union
The \textbf{probability union} of two events \( E \) and \( F \) is the probability that at least one of the events occurs. It's shown as \( P(E \cup F) \) and can be understood through the inclusive 'or' logic, which signifies 'either this, that, or both'.

For mutually exclusive events where the probability of intersection is zero, the probability of the union is simply the sum of their individual probabilities: \( P(E \cup F) = P(E) + P(F) \). But when events are not mutually exclusive, and they can occur together, we subtract the intersection from the total to avoid double counting: \( P(E \cup F) = P(E) + P(F) - P(E \cap F) \). This ensures we account for each distinct outcome.
Independent Events
Lastly, let's explore \textbf{independent events}. Two events are considered independent if the outcome of one event does not influence the outcome of the other. For instance, flipping a coin and rolling a die are independent events because the result of the coin flip doesn't affect the die roll.

To determine if events are independent, you can test whether the probability of one event occurring affects the probability of the other event. Mathematically, if \( A \) and \( B \) are independent, then \( P(A \cap B) = P(A)*P(B) \). If this equation holds true, then you've shown that the occurrence of event \( A \) has no bearing on the probability of event \( B \) occurring, and vice versa.

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Most popular questions from this chapter

A large cable company reports that \(80 \%\) of its customers subscribe to its cable TV service, \(42 \%\) subscribe to its Internet service, and \(97 \%\) subscribe to at least one of these two services. a. Use the given probability information to set up a hypothetical 1000 table. b. Use the table from Part (a) to find the following probabilities: i. the probability that a randomly selected customer subscribes to both cable TV and Internet service. ii. the probability that a randomly selected customer subscribes to exactly one of these services.

In a January 2016 Harris Poll, each of 2252 American adults was asked the following question: "If you had to choose, which ONE of the following sports would you say is your favorite?" ("Pro Football is Still America's Favorite Sport," www.theharrispoll.com/sports/Americas_Fav_Sport_2016. html, retrieved April 25,2017 ). Of the survey participants, \(33 \%\) chose pro football as their favorite sport. The report also included the following statement, "Adults with household incomes of \(\$ 75,000-<\$ 100,000(48 \%)\) are especially likely to name pro football as their favorite sport, while love of this particular game is especially low among those in \(\$ 100,000+$$ households \)(21 \%)\( Suppose that the percentages from this poll are representative of American adults in general. Consider the following events: \)F=\( event that a randomly selected American adult names pro football as his or her favorite sport \)L=\( event that a randomly selected American has a household income of \)\$ 75,000-<\$ 100,000\( \)H=\( event that a randomly selected American has a household income of \)\$ 100,000+$$ b. Are the events \(F\) and \(L\) mutually exclusive? Justify your answer. c. Are the events \(H\) and \(L\) mutually exclusive? Justify your answer. d. Are the events \(F\) and \(H\) independent? Justify your answer.

Six people hope to be selected as a contestant on a TV game show. Two of these people are younger than 25 years old. Two of these six will be chosen at random to be on the show. a. What is the sample space for the chance experiment of selecting two of these people at random? (Hint: You can think of the people as being labeled \(\mathrm{A}, \mathrm{B}, \mathrm{C}, \mathrm{D}, \mathrm{E},\) and \(\mathrm{F}\). One possible selection of two people is \(\mathrm{A}\) and \(\mathrm{B}\). There are 14 other possible selections to consider.) b. Are the outcomes in the sample space equally likely? c. What is the probability that both the chosen contestants are younger than \(25 ?\) d. What is the probability that both the chosen contestants are not younger than \(25 ?\) e. What is the probability that one is younger than 25 and the other is not?

a. Suppose events \(E\) and \(F\) are mutually exclusive with \(P(E)=0.64\) and \(P(F)=0.17\) i. What is the value of \(P(E \cap F)\) ? ii. What is the value of \(P(E \cup F)\) ? b. Suppose that \(A\) and \(B\) are events with \(P(A)=0.3, P(B)=0.5\), and \(P(A \cap B)=0.15 .\) Are \(A\) and \(B\) mutually exclusive? How can you tell? c. Suppose that \(A\) and \(B\) are events with \(P(A)=0.65\) and \(P(B)=0.57 .\) Are \(A\) and \(B\) mutually exclusive? How can you tell?

In an article that appears on the website of the American Statistical Association, Carlton Gunn, a public defender in Seattle, Washington, wrote about how he uses statistics in his work as an attorney. He states: I personally have used statistics in trying to challenge the reliability of drug testing results. Suppose the chance of a mistake in the taking and processing of a urine sample for a drug test is just 1 in 100 . And your client has a "dirty" (i.e., positive) test result. Only a 1 in 100 chance that it could be wrong? Not necessarily. If the vast majority of all tests given say 99 in 100 -are truly clean, then you get one false dirty and one true dirty in every 100 tests, so that half of the dirty tests are false. Define the following events as \(T D=\) event that the test result is dirty \(T C=\) event that the test result is clean \(D=\) event that the person tested is actually dirty \(C=\) event that the person tested is actually clean a. Using the information in the quote, what are the values of $$ \text { i. } P(T D \mid D) $$ iii. \(P(C)\) $$ \text { ii. } P(T D \mid C) $$ iv. \(P(D)\) b. Use the probabilities from Part (a) to construct a hypothetical 1000 table. c. What is the value of \(P(T D)\) ? d. Use the information in the table to calculate the probability that a person is clean given that the test result is dirty, \(P(C \mid T D)\). Is this value consistent with the argument given in the quote? Explain.

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