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Quiz #3 Stat211: Business Statistics I Term 072 KFUPM Dept of Math & Statistics
Instructor: Dr. Mohammad H. Omar Section: 1 (9am), 2 (10am) or 4(1pm) ID#:__________
Serial #:_________Name:___________________________
Directions: This quiz is designed for 20 minutes. Answer some selected questions based on instrcutor’s directions. Show
your work in detail and write neatly and legibly.
1. If the age distribution of customers at a major retail chain is thought to be bell-shaped with a mean equal
to 43 years and a standard deviation equal to 7 years, the percentage of customers between the ages of
29 and 50 years is:
(a) about 95.
(b) about 81.5. () (c) at least 75. (d) about 68.
2. The following data reflect the number of customers who test drove new cars each of a sample of 20 days.
5
9
7
7
2
10
9
4
4
7
5
6
6
3
4
4
0
14
7
6
Given these data, what is the inter-quartile range?
(a) 3 ()
(b) 4
(c) 7
(d) 14
3. A company has two assembly lines. Line A produces an average of 335 units per day with a standard
deviation equal to 11 units. Line B produces an average of 145 units per day with a standard deviation
equal to 8 units.
a. What is the coefficient of variation for Line A. Line A: CV= 11/335*100% = 3.283582%
b. What is the coefficient of variation for Line B. Line B: CV= 8/145*100% = 5.51724%
c. Which Line (Line A/Line B) is relatively more consistent? Line w/ smaller CV is more consistent
4. Consider the following data as representing the population of cars sold in each of 8 weeks
3
5
2
7
7
7
9
0
n
Find the standard deviation of cars sold. (Hint: The mean is 5 cars)  X i2  32  52  ...  02  266
i 1
1 n 
i1 ( X i  X ) i1 X  n  i1 X i 


n 1
n 1
n
N
2

 40 
266 
8
2
2
i
2
8  66  8.25  2.872281323
8
5. The following sample data reflect electricity bills for ten households in San Diego in March. Determine
three measures of central tendency for these sample data. Then, based on these measures, determine
whether the sample data are symmetric or skewed. ( Symmetric, Skewed )
118.20 67.88 133.40 88.42 110.34
76.90 144.56 127.89 89.34 129.10
mean=
median=
mode=
1086.03
108.603
114.27
no mode
Form A: Questions 1, 4
Form B: Questions 2, 3
Form C: Questions 1, 5
Form D: Questions 2, 4
Quiz #3B Stat211: Business Statistics I Term 072 KFUPM Dept of Math & Statistics
Instructor: Dr. Mohammad H. Omar Section: 2 (8-8.50am) or 1 (9-9.50am) ID#:__________
Serial #:_________Name:___________________________
Directions: This quiz is designed for 20 minutes. Show your work in detail and write neatly and legibly
2. A store manager tracks the number of customer complaints each week. The following
data reflect a random sample of ten weeks.
11
19
4
6
8
9
6
4
0
3
The standard deviation for these data is approximately 27.78. ( True , False )
3. At a recent meeting, the production manager at Harris Manufacturing stated that the
coefficient of variation for units produced daily at her plant was 55 percent. She also
stated that the mean production volume was 11,200 units per day. Based on this
information, the standard deviation of production volume is approximately 6,160 units.
( True , False )
4. A small company has 7 employees. The numbers of years these employees have worked
for this company are shown as follows:
4 14 3
16
9
8
16
Based upon this information, the median number of years that employees have been
with this company is:
a. 9 years.
b. 16 years.
c. 10 years.
d. None of the above.
5. The advantage of using the inter-quartile range versus the range as a measure of variation
is:
a. it is easier to compute.
b. it utilizes all the data in its computation.
c. it gives a value that is closer to the true variation.
d. it is less affected by extremes in the data.
6. The distribution of actual weight of potato chips in a 16 ounce sack is thought to be bellshaped with a mean equal to 16 ounces and a standard deviation equal to 0.45 ounces.
Based on this, between what two limits could we expect 95 percent of all sacks to
weigh?
a. 14 to 18 ounces
b. 15.10 to 16.90 ounces
c. 15.55 to 16.45 ounces
d. None of the above.
7. If a business manager selected a sample of customers and computed the mean income for
this sample of customers, she has computed:
a. a statistic.
Quiz #3B Stat211: Business Statistics I Term 072 KFUPM Dept of Math & Statistics
Instructor: Dr. Mohammad H. Omar Section: 2 (8-8.50am) or 1 (9-9.50am) ID#:__________
Serial #:_________Name:___________________________
Directions: This quiz is designed for 20 minutes. Show your work in detail and write neatly and legibly
b. an ordinal value.
c. a nominal value.
d. None of the above.
8. The following data reflect the number of customers who return merchandise for a refund
on Monday. Note these data reflect the population of all 10 Mondays for which data are
available.
Assume that this same exact pattern of data were replicated for the next ten days. How
would this affect the standard deviation for the new population with 20 items?
a. The standard deviation would be doubled.
b. The standard deviation would be cut in half.
c. The standard deviation would not be changed.
d. There is no way of knowing the exact impact.
9. In the annual report, a major food chain stated that the distribution of daily sales at their
Detroit stores is known to be bell-shaped, and that 95 percent of all daily sales fell
between $19,200 and $36,400. Based on this information, what were the mean sales?
a. Around $20,000
b. Close to $30,000
c. Approximately $27,800
d. Can’t be determined without more information.