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Stats Modeling the World 3rd Edition By David E. Bock – Test Bank
Chapter 4
MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.
1) Which of these random variables is most likely to have a binomial model? 1)
A) The number of people we check until we find someone with green eyes. B) The number of cards of each suit in a 10-card hand.
C) The number of aces among the top 10 cards in a well-shuffled deck.
D) The number of Democrats among a group of 20 randomly chosen adults. E) The number of cars inspected until we find three with bad mufflers.
Answer: D Explanation: A)
B) C) D) E)
2) Which two events are most likely to be independent? 2) A) having a flat tire, and being late for school
B) having a driver’s license, and having blue eyes
C) getting an A in math, and getting an A in Physics
D) having a car accident, and having 3 inches of snow today E) being a senior, and leaving campus for lunch
Answer: B Explanation: A)
B) C) D) E)
3) Which of these random variables has a geometric model? 3) A) The number of people we check until we find someone with green eyes.
B) The number of cars inspected until we find three with bad mufflers.
C) The number of aces among the top 10 cards in a well-shuffled deck.
D) The number of cards of each suit in a 10-card hand.
E) The number of Democrats among a group of 20 randomly chosen adults.
Answer: A Explanation: A)
B) C) D) E)
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4) Which two events are most likely to be independent? 4)
A) registering to vote; being left-handed
B) being a senior; going to homeroom
C) having a car accident; having a junior license
D) having 3 inches of snow in the morning; being on time for school E) doing the Statistics homework; getting an A on the test
Answer: A Explanation: A)
B) C) D) E)
5) Which of these has a geometric model? 5) A) The colors of the cars in the grocery store parking lot.
B) The number of hits a baseball player gets in 6 times at bat.
C) The number of black cards in a 10-card hand.
D) The number of cards drawn from a deck until we find all four aces.
E) The number of people we survey until we find someone who owns an iPod.
Answer: E Explanation: A)
B) C) D) E)
6) Which of these has a Geometric model? 6) A) the number of sodas students drink per day
B) the number of aces in a five-card Poker hand
C) the number of people we survey until we find two people who have taken Statistics D) the number of people we survey until we find someone who has taken Statistics
E) the number of people in a class of 25 who have taken Statistics
Answer: D Explanation: A)
B) C) D) E)
7) Which of these has a Binomial model? 7) A) the number of people in a class of 25 who have taken Statistics
B) the number of people we survey until we find someone who has taken Statistics
C) the number of sodas students drink per day
D) the number of people we survey until we find two people who have taken Statistics E) the number of aces in a five-card Poker hand
Answer: A Explanation: A)
B) C) D) E)
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8) Which of those choices listed in problem 7 is most likely to have a binomial model? 8)
A) The number of hits a baseball player gets in 6 times at bat.
B) The number of black cards in a 10-card hand.
C) The number of people we survey until we find someone who owns an iPod.
D) The colors of the cars in the grocery store parking lot
E) The number of cards drawn from a deck until we find all four aces.
Answer: A Explanation: A)
B) C) D) E)
9) A fair coin has come up “heads” 10 times in a row. The probability that the coin will come up heads 9) on the next flip is
A) It cannot be determined.
B) greater than 50%, since it appears that we are in a streak of “heads.” C) less than 50%, since “tails” is due to come up.
D) 50%.
Answer: D Explanation: A)
B) C) D)
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SHORT ANSWER. Write the word or phrase that best completes each statement or answers the question.
A sporting goods store announces a “Wheel of Savings” sale. Customers select the merchandise they want to purchase, then at the cash register they spin a wheel to determine the size of the discount they will receive. The wheel is divided into 12 regions, like a clock. Six of those regions are red, and award a 10% discount. The three white regions award a 20% discount and two blue regions a 40% discount. The remaining region is gold, and a customer whose lucky spin lands there gets a 100% discount – the merchandise is free! Show your work.
10) As you wait your turn in line there are three gold winners in a row. A lively discussion 10) ensues between the next two customers. One thinks that streak about kills her chances of winning free merchandise, as the wheel won’t come up gold again for a very long time.
The other says that the wheel is clearly on a hot streak, so they are lucky to be next in line. Comment on their opinions.
Answer: The spins are independent, so if the wheel is fair the three gold winners in a row have no effect on the next person’s chances. The first argument is based on the Law of Averages, and certainly wrong. If the wheel is somehow unbalanced to favor the gold space, the second argument might be valid, but we haven’t enough evidence to suggest this is true.
Explanation:
A new clothing store advertises that during its Grand Opening every customer that enters the store can throw a bouncy rubber cube onto a table that has squares labeled with discount amounts. The table is divided into ten regions. Five regions award a 10% discount, two regions award a 20% discount, two regions award a 30% discount, and the remaining region awards a 50% discount. Show your work.
11) What is the probability that the first two customers both get a 50% discount? 11)
Answer: P(50 50) = P(50) ·P(50) = 1 2= 1 = 0.01 10 100
Explanation:
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