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A SAMPLE TEST OF BUSINESS STATISTICS (90 MINUTES)
STUDENT NAME: STUDENT ID:
Choose the one alternative that best answers the question.
1) A population has groups that have a small amount of variation within them, but large variation among
or between the groups themselves. The proper sampling technique is
A) simple random. B) stratified.
C) cluster. D) judgment.
2) The distribution pictured below is
A) bimodal and skewed right. B) bimodal and skewed left.
C) skewed right. D) skewed left.
3) Bob found an error in the following frequency distribution. What is it?
Class
Frequency
1–10
2
11–20
6
25–30
8
31–40
12
44–50
6
A) The class limits are overlapping too much.
B) The classes are not collectively exhaustive.
C) There are too many classes by Sturges’ Rule.
D) The first class must start at 0.
4) Below is a sorted stem-and-leaf diagram for the measured speeds (miles per hour) of 49 randomly
chosen vehicles on highway I-80 in Nebraska. How many vehicles were traveling exactly the speed limit
(70 mph)?
Stem unit
=
10
Leaf unit
=
1
Frequency
Stem
Leaf
1
4
9
1
5
5
17
6
0 1 2 2 2 4 5 5 5 5 6 6 8 8 9 9 9
19
7
0 1 1 1 2 3 3 3 4 5 6 6 6 7 7 8 9 9 9
7
8
0 1 3 3 5 5 7
4
9
0 1 2 2
49
A) 0 B) 1
C) 19 D) Impossible to tell
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5) Shown the spending by a sample of 50 breakfast customers of McDonald’s. Which statement is least
likely to be correct?
A) The median is very close to the midhinge.
B) The median purchase is slightly less than $5.
C) About 75 percent of the customers spend less than $7.
D) The mean is a reasonable measure of center.
6) Given the contingency table shown here, find P(G | M).
Vehicle Type
Somerset
(S)
Oakland
(O)
Great Lakes
(G)
Row Total
Car (C)
44
49
36
129
Minivan (M)
21
15
18
54
Full-Size Van (F)
2
3
3
8
SUV (V)
19
27
26
72
Truck (T)
14
6
17
37
Col Total
100
100
100
300
A) .1800 B) .0450
C) .3333 D) .1350
7) The manager of Ardmore Pharmacy knows that 25 percent of the customers entering the store buy
prescription drugs, 65 percent buy over-the-counter drugs, and 18 percent buy both types of drugs. What
is the probability that a randomly selected customer will buy at least one of these two types of drugs?
A) .90 B) .85
C) .72 D) .65
8) In a certain city, 5 percent of all drivers have expired licenses and 10 percent have an unpaid parking
ticket. If these events are independent, what is the probability that a driver has both an expired license and
an unpaid parking ticket?
A) .010 B) .005
C) .001 D) Cannot be determined
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9) At Joe’s Restaurant, 80 percent of the diners are new customers (N), while 20 percent are returning
customers (R). Fifty percent of the new customers pay by credit card, compared with 70 percent of the
regular customers. If a customer pays by credit card, what is the probability that the customer is a new
customer?
A) .7407 B) .8000
C) .5400 D) .5000
10) To ensure quality, customer calls for airline fare quotations are monitored at random. On a particular
Thursday afternoon, ticket agent Bob gives 40 fare quotations, of which 4 are incorrect. In a random
sample of 8 of these customer calls, which model best describes the number of incorrect quotations Bob
will make?
A) Binomial B) Poisson
C) Hypergeometric D) Geometric
11) A carnival has a game of chance: a fair coin is tossed. If it lands heads you win $1.00, and if it lands
tails you lose $0.50. How much should a ticket to play this game cost if the carnival wants to break even?
A) $0.25 B) $0.50
C) $0.75 D) $1.00
12) A clinic employs nine physicians. Five of the physicians are female. Four patients arrive at once.
Assuming the doctors are assigned randomly to patients, what is the probability that all of the assigned
physicians are female?
A) .0397 B) .0295
C) .0808 D) .0533
13) On average, 15 minutes elapse between discoveries of fraudulent corporate tax returns in a certain
IRS office. What is the probability that less than 30 minutes will elapse before the next fraudulent
corporate tax return is discovered?
A) .1353 B) .6044
C) .7389 D) .8647
14) A software developer makes 175 phone calls to its current customers. There is an 8 percent chance of
reaching a given customer (instead of a busy signal, no answer, or answering machine). The normal
approximation of the probability of reaching at least 20 customers is
A) .022 B) .007
C) .063 D) .937
15) A random sample of 160 commercial customers of PayMor Lumber revealed that 32 had paid their
accounts within a month of billing. The 95 percent confidence interval for the true proportion of
customers who pay within a month would be
A) 0.148 to 0.252 B) 0.138 to 0.262
C) 0.144 to 0.256 D) 0.153 to 0.247
16) The owner of Limp Pines Resort wanted to know the average age of its clients. A random sample of
25 tourists is taken. It shows a mean age of 46 years with a standard deviation of 5 years. The width of a
98 percent confidence interval for the true mean client age is approximately
A) ±1.711 years. B) ±2.326 years.
C) ±2.492 years. D) ±2.797 years.
17) Jolly Blue Giant Health Insurance (JBGHI) is concerned about rising lab test costs and would like to
know what proportion of the positive lab tests for prostate cancer are actually proven correct through
subsequent biopsy. JBGHI demands a sample large enough to ensure an error of ±2 percent with 90
percent confidence. What is the necessary sample size?
A) 4,148 B) 2,401
C) 1,692 D) 1,604
18) A sample of 16 ATM transactions shows a mean transaction time of 67 seconds with a standard
