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Chapter 4-1:

Terms in this set (17)

If A denotes some event, what does Ā denote? If P(A)=0.996, what is the value of P(Ā)?

a) Event Ā is always unusual.
b) Event Ā denotes the complement of event A, meaning that Ā and A share some but not all outcomes.
c) Events A and Ā share all outcomes.
d) Event Ā denotes the complement of event A, meaning that Ā consists of all outcomes in which event A does not occur.

If P(A)=0.996, what is the value of P(Ā)?
d) Event Ā denotes the complement of event A, meaning that Ā consists of all outcomes in which event A does not occur.

P(Ā)=0.004
1-0.996=0.004
A weather forcasting website indicated that there was a 10% chance of rain ina certain region. Based on that report, which of the followin is the most resonable interpretation?

a) There is a 0.10 probability that it will rain somewhere in the region at ssome point during the day.
b) 10% of the region will get rain today.
c) In the region, it will rain for 10% of the day.
d) None of the above interpretations are reasonable.
a) There is a 0.10 probability that it will rain somewhere in the region at ssome point during the day.
Seventeen of the 100 digital video recorders (DVRs) in an inventory are known to be defective. What is the probability that a randomly selected item is defective?
The probability is .17

17/100=0.17
For a certain horse race, the odds in favor of a certain horse finishing in second place are given as 43 to 57. Express the indicated degree of likelihood as a probability value between 0 and 1 inclusive.
The probability is .43.
In a certain weather forecast, the chances of a thunderstorm are stated as "5 in 24." Express the indicated degree of likelihood as a probability value between 0 and 1 inclusive.
The probability is 0.208
5/24=0.208
In a certain study, the chance of encountering a car crash on the road is stated as 14%. Express the indicated degree of likelihood as a probability value between 0 and 1 inclusive.
The probability is 0.14.
14/100=0.14
Express the indicated degree of likelihood as a probability value between 0 and 1.

When using a computer to randomly generate the last digit of a phone number to be called for a survey, there is 1 chance in 10 that the last digit is zero.
The probability is 0.1.
1/10=0.1
Express the indicated degree of likelihood as a probability value between 0 and 1.

Based on a survey of hiring managers who were asked to identify the biggest mistakes that job candidates make during an interview, there is a 50-50 chance that they will identify "inappropriate attire."
The probability is .50.
50/100=.50
You are certain to get a black or a red card when selecting cards from a shuffled deck. Express the indicated degree of likelihood as a probability value between 0 and 1 inclusive.
The probability is 1.
CERTAIN=1
You are certain to get 3 jacks when selecting 51 cards froma shuffled deck. Express the indicated degree of likelihood as a probability value between 0 and 1 inclusive.
The probability is 1.
CERTAIN=1
Refer to the sample data for pre-employment drug screen shown below. If one of the subjects is randomly selected, what is the probability that the test result is a false positive? Who would suffer from a faluse positive result? Why?

Pre-Employment Drug Screening Results
Subject Uses Drugs
Positive Result 47
Negative Results 8
Subject is Not a Drug User
Positve Results 2
Negative Results 27

The proability of a false positve test result is _____.

Who would suffer from a false positive result? Why?
a) The employer would suffer because the person tested would not be suspected of using drugs when in reality he or she does use drugs.
b) The person tested would suffer because he or she would not be suspected of using drugs when in reality he or she does use drugs.
c) The person tested would suffer because he or she would be suspected of using drugs when in reality he or she does not use drugs.
d) The employer would suffer because the person tested would be suspected of using drugs when in reality he or she does not use drugs.
The probability of a false positive test result is 0.024.
2/84=0.024

c) The person tested would suffer because he or she would be suspected of using drugs when in reality he or she does not use drugs.
One their first date, Kelly asks Mike to guess the date of her birth, not including the year. Complete parts a through 1-3 below.

1. What is the probability that Mike will guess correctly?

2. Would it be unlikely for him to guess correctly on his first try?
a) Yes, it is unlikely for Mike to guess correctly on his first try, as the probability of a correct guess is very low.
b) No, it is not unlikely for Mike to guess correctly on his first try, as the probability of a correct guess is very low.
c) No, it is not unlikely for Mike to guess correctly on his first try, as the probability of a correct guess is very high.
d) Yes, it is unlikely for Mike to guess correctly on his first try, as the probability of a correct guess is very high.
e) It is impossible for Mike to not guess correctly on his first try, as the probability of a correct guess is 1.
f) If is impossible for Mike to guess correctly on his first try, as the probability of a correct guess is 0.

3. If you were Kelly, and Mike did guess correctly on his first try, would you believe his claim that he made a lucky guess, or would you be convinced that he already knew when you were born?

Mike __________ as the probability of a correct guess is __________.
1. 1/365
There are 365 days in a year.

2. a) Yes, it is unlikely for Mike to guess correctly on his first try, as the probability of a correct guess is very low.

3. Mike already knew, as the probability of a correct guess is very low.
To the right are the outcomes tht are possible when a couple has three children. Assume that boys and girls are equally likely, so that the eight simple events are equally likely. Find the probability that when a couple has three children, there are exactly 0 girls.

1st - 2nd - 3rd
boy-boy-boy
boy-boy-girl
boy-girl-boy
boy-girl-girl
girl-boy-boy
girl-boy-girl
girl-girl-boy
girl-girl-girl

What is the probability of exactly 0 grils out of three children?
1/8
The sample space listing the eight simple events that are possible when a couple has three chilren is {bbb, bbg, bgb, bgg, gbb, gbg, ggb, ggg}. After identifying the sample space for a couple having four children, find the probability of getting four girls and no boys.

Identify the sample sapece for a couple having four children.

Find the probability of getting four girls and no boys.
Identify the sample space for a couple having four children.
{gggg, bggg, gbgg, ggbg, gggb, bbgg, bgbg, bggb, gbbg, gbgb, ggbb, bbbg, bbgb, bgbb, gbbb, bbbb}

Find the probability of getting four girls and no boys.
0.0625
1/16=0.0625
The __________ for a procedure consists of all possible simple events or all outcomes that cannot be broken down any further.
sample space
The classical appraoch to probability requires that the outcomes are __________.
equally likely.
As a procedure is repeated again and again, the relative frequency of an event tends to approach the actual probability. This is known as __________.
the law of large numbers.
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