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Chapter 5: Randomness and Probability – Quiz A
Name_____________________________________
5.4.1 Find probabilities and/or determine independence.
1. During a promotion, Christina’s department store offers a mailing “scratch a winner –
discount savings.” After customers select the items they wish to purchase, they scratch
their discount sticker from the mailing to determine the discount they will receive. The
scratch wheel is divided into 12 slices. Six slices are red and award a 10% discount,
three slices are white and award a 20% discount, and two slices are blue and award a 40%
discount. The remaining slice is gold and awards a 100% discount if the customer
scratches that slice!
a. What is the probability that a customer gets at least a 40% discount?
b. What is the probability that a customer does not get at least a 40% discount?
c. What is the probability that a customer gets a 10% or 20% discount?
d. What is the probability that two customers in a row get a 20% discount?
5.4.1 Use and understand the concepts and definitions of probability.
2. Suppose you visit Christina’s department store in the hopes of getting a 100%
discount on your purchases. As you wait your turn in line, there are three gold winners in
a row. The two customers in line behind you begin to discuss what’s happened. One
believes that the streak of three gold winners has killed anyone else’s chances of getting a
100% discount, while the other says just the opposite… that the wheel’s “hot streak”
increases their chances of getting a 100% discount. Comment on these opinions.
5.4.1 Find probabilities and/or determine independence.
3. A recent survey of local cell phone retailers showed that of all smart phones sold last
month, 64% of buyers also owned a tablet of laptop, 28% also owned an iPod type music
player and 22% owned both.
a. What is the probability that a smart phone buyer also owned a tablet/ laptop or a music
player?
5-2 Chapter 5 Randomness and Probability
b. What is the probability that a smart phone buyer did not also own either a tablet/ laptop
or a music player?
c. Is a smart phone buyer owning a tablet/laptop in addition to a music player mutually
exclusive? Explain.
5.5.2 Find probabilities and/or determine independence.
4. A small manufacturing company recently instituted Six Sigma training for its
employees. Two methods of training were offered: online and traditional classroom.
Management was interested in whether the division in which employees worked affected
their choice of method. Below is a table summarizing the data.
a. What is the probability that an employee chose online training?
b. What is the probability that an employee is in the quality division and chose online
training?
c. What is the probability that an employee chose online training given that he/she is in
the sales division?
5.5.2 Find probabilities and/or determine independence.
5. Does it appear that choice of instructional method (traditional or online) and division
(sales, quality and operations) are independent? Explain.
5.5.2 Find probabilities and/or determine independence.
6. One explanation put forth for the dearth of women CEO’s in the high tech industry is
that there are a lack of mentoring opportunities for women. A recent survey of CEO’s in
that industry found that 80% were men. Moreover, 75% had been mentored while only
15% were women and had been mentored.
a. Construct the contingency table.
b. Are gender and mentoring independent? Explain.
Sales Quality Operations Total
Traditional 16 10 8 34
Online 35 23 44 102
Total 51 33 52 136
Quiz A 5-3
Chapter 5: Randomness and Probability – Quiz A – Key
5-4 Chapter 5 Randomness and Probability
Quiz A 5-5
5-6 Chapter 5 Randomness and Probability
Chapter 5: Randomness and Probability – Quiz B
Name_____________________________________
5.4.1 Find probabilities and/or determine independence.
1. As an incentive to get new customers, the local branch of a bank launched “bouncing
for bucks.” During this week long event, any customer opening a new checking account
with the bank would have the opportunity to throw a bouncy rubber ball into a large box
divided into squares. Each square was labeled with a dollar amount that would be
deposited into his/her new checking account. The way the box was labeled is shown
below.
10 30 10 30 10
20 10 50 10 20
a. What is the probability that a customer gets $20 or more?
b. What is the probability that a customer gets less than $20?
c. What is the probability that a customer gets $20 or $30?
d. What is the probability that two customers in a row get $50?
5.4.1 Use and understand the concepts and definitions of probability.
2. As you enter the bank, you watch four persons in front of you all win $50. The local
branch manager tells you how lucky you are to be throwing the ball while it is on a hot
streak but the friend with you says that you’re unlucky because the streak can’t continue.
Comment on their statements.
5.4.1 Find probabilities and/or determine independence.
3. A major airline keeps track of data on how their passengers redeem frequent flyer
miles. They found that in the last year 58% of passengers redeemed them to purchase
tickets for domestic travel, 44% redeemed them to purchase tickets for international
travel, and that 16% redeemed them to purchase tickets for both domestic and
international travel.
a. What is the probability that in the last year a passenger redeemed frequent flyer miles
to purchase a ticket for domestic or international travel?
b. What is the probability that in the last year a passenger did not redeem frequent flyer
miles to purchase a ticket for domestic or international travel?
c. Is redeeming frequent flyer miles to purchase a ticket for domestic and international
travel mutually exclusive? Explain.
Quiz B 5-7
5.5.2 Find probabilities and/or determine independence.
4. The option to buy extended warranties is commonplace with most electronics
purchases. But does the type of purchase affect a consumer’s willingness to pay extra for
an extended warranty? Data for 420 consumers who purchased big screen TVs and
laptop computers from a leading electronics retailer are summarized in the table.
a. What is the probability that a consumer purchases an extended warranty?
b. What is the probability that a consumer purchases a big screen TV and an extended
warranty?
c. What is the probability that a consumer purchases an extended warranty given that
he/she has purchased a big screen TV?
5.5.2 Find probabilities and/or determine independence.
5. Does it appear that the decision to purchase an extended warranty and type of
electronics (big screen TV or laptop computer) purchased are independent? Explain.
5.5.2 Find probabilities and/or determine independence.
6. It has been reported that men are more likely than women to participate in online
auctions. A recent study found that 52% of Internet shoppers are women and that 35% of
Internet shoppers have participated in online auctions. Moreover, 25% of online
shoppers were men and had participated in online auctions.
a. Construct the contingency table.
b. Are gender and participation in online auctions independent? Explain.
Purchased Warranty?
Yes No Total
Big Screen TV 30 42 72
Laptop Computer 145 203 348
Total 175 245 420
5-8 Chapter 5 Randomness and Probability
Chapter 5: Randomness and Probability – Quiz B – Key
Quiz B 5-9
5-10 Chapter 5 Randomness and Probability
Quiz C 5-11
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Chapter 5: Randomness and Probability – Quiz C – Multiple Choice
Name_____________________________________
5.4.1 Find probabilities and/or determine independence.
1. During a promotion, Christina’s department store offers a mailing “scratch a winner –
discount savings.” After customers select the items they wish to purchase, they scratch
their discount sticker from the mailing to determine the discount they will receive. The
scratch wheel is divided into 12 slices. Six slices are red and award a 10% discount,
three slices are white and award a 20% discount, and two slices are blue and award a 40%
discount. The remaining slice is gold and awards a 100% discount if the customer
scratches that slice! The probability that a customer gets at least a 40% discount is
A. 3/12
B. 2/12
C. .0625
D. 9/12
E. 10/12
5.1. Use and understand the concepts and definitions of probability.
2. During a promotion, Christina’s department store offers a mailing “scratch a winner –
discount savings.” After customers select the items they wish to purchase, they scratch
their discount sticker from the mailing to determine the discount they will receive. The
scratch wheel is divided into 12 slices. Six slices are red and award a 10% discount,
three slices are white and award a 20% discount, and two slices are blue and award a 40%
discount. The remaining slice is gold and awards a 100% discount if the customer
scratches that slice! The probability that a customer gets a 10% or 20% discount is
A. 3/12
B. 2/12
C. .0625
D. 9/12
E. 10/12