# True or False questions: by CGs31n1

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```									    KING FAHD UNIVERSITY OF PETROLEUM & MINERALS
DEPARTMENT OF MATHEMATICAL SCIENCES
DHAHRAN, SAUDI ARABIA
STAT 211: BUSINESS STATISTICS I
Semester 062
Mid Term Exam No.1
Wednesday March 28, 2007
5:30 – 7:15 pm

Instructor’s name    &     section number
Prof. Hassen A .Muttlak               1
Mohammad F. Saleh           2         3      4

Name:                               Student ID#:               Serial #:

Directions:
1) You must show all work to obtain full credit for questions on this exam.
2) DO NOT round your answers at each step. Round answers only if necessary
at your final step to 4 decimal places.

Question No Full Marks Marks Obtained
Part One          8
Part Two          8
Q1           12
Q2             5
Q3             5
Q4            10
Q5            22
Total          70
STAT 211 Business Statistics I – Term 062, Major 1

Part One (8 pts, 1 for each)
Indicate which of the following TRUE or FALSE
1. The classes in any frequency distribution are both all inclusive and mutually
exclusive._______

2. A tire store manager has collected data showing the number of tires of each
brand sold during the past month. A bar chart might be effective in
graphically illustrating which brands tend to sell best at this store. _______

3. One of the most effective methods for displaying the trend in the number of
traffic accidents over the past ten years is to use a scatter plot showing the
number of vehicles on one axis and the number of accidents on the second
axis. _______

4. Telephone surveys are most frequently used for political polls. The reason is
that the survey can be conducted in a shorter time span (usually over a 24
hour period.) _______

5. When students are asked to list their age and the percentage of their college
expenses that they pay for themselves, the type of data being collected is
quantitative. _______

6. When a group of university students take a poll of their fellow students on
whether they support a proposed fee increase, the sampling method they
would use when students walking near the library are surveyed would be
called a random sample. _______

7. If you wish to select a non statistical sample of opinions from customers at a
particular market, the method that you might consider using is cluster
sampling. ______

8. A small engine repair shop tracks the number of customers who call each
day. This variable is a time series variable and also ratio level._______

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STAT 211 Business Statistics I – Term 062, Major 1

Part Two (8 pts 1 for each)
Circle the correct answer:
1. Which of the following statements about histogram is correct?

a. The rectangles (bars) are proportional in height to the number of items
falling in the classes
b. There are generally five rectangles (bars) in each histogram
c. The area in a rectangle (bar) depends only on the number of items in the
class compared to the number of items in all other classes.
d. Narrow class intervals can obscure important patterns of variation.

2. The Fitness Center manager has collected data on the number of visits to the
club each week for the past 8 weeks. These data are shown as follows. Which
of the following statements is most correct?

Week 1      Week 2       Week 3      Week 4    Week 5   Week 6   Week 7   Week 8
1415        1623         1934        1879      2102     2156     2511     2499

a. A histogram will illustrate whether a linear relationship exists between
the number of visits and the week number.
b. A scatter diagram would be useful for displaying these data.
c. A line chart for these data will show that an upward trend in the number
of visits to the club has occurred over the past 8 weeks.
d. The proper graph for displaying these data is a pie chart.

3. A scatter diagram can be used to do which of the following?

a.   Determine the trend in a variable
b.   Analyze the relationship between two variables
c.   Describe the basic distribution for a quantitative variable
d.   Show the percentage of a variable that is associated with each category
into which that variable has been divided.

4. The mode has all the following disadvantages except

a.   A data set may have no model value.
b.   Every value in a data set may be a mode.
c.   The mode may not reflect the center of a data.
d.   The mode is not effected by the extreme values

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STAT 211 Business Statistics I – Term 062, Major 1

5. Which of the following statements in NOT correct?

a. Calculation of a mean is affected by the extreme values.
b. The median is the preferred measure of central location for ordinal data
instead of the mean.
c. The mean can be found for all levels of data measurements.
d. The sum of the differences between each observation in a data set and the
mean of the data set always zero.

6. A tire manufacturing company is interested in obtaining data on stopping
distances for each of the three main tread types made by the company. The
data collection method that would be most likely used in this case would be:

a.   Telephone survey.
b.   Written questionnaire.
c.   Demographic surveying.
d.   Experiments.

7. Under what circumstances is it necessary to use the coefficient of variation to
compare relative variability between two or more distributions

a.   When the means of the distributions are equal
b.   When the means of the distributions are not equal
c.   When the standard deviations of the distributions are not equal
d.   When the standard deviations of the distributions are equal

8. The human resources department at a major high tech company recently
conducted an employee satisfaction survey of 100 of its 3,000 employees.
Data were collected on such variables as age, gender, marital status, current
salary, level of overall satisfaction on a scale from 1 to 5, number of years with
the company, and job title. Which of the variables would be considered to be
qualitative data?

a.   Gender, marital status, job satisfaction, and job title
b.   Age
c.   Years with the company
d.   All variables listed are qualitative.

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STAT 211 Business Statistics I – Term 062, Major 1

Part Three
Question One (6+3+3 pts):
A computer company compiled data regarding the number of interviews required
for each of its 40 salespeople to make a sale. Following are a frequency
distribution and a relative frequency distribution of the number of interviews
required per salesperson per sale.

a. Fill the missing data

Number of interviews Frequency          Relative frequency
0.200
10

0.150
[40 – 50)                              0.025
Total

b. Construct a frequency histogram.

c. Explain what information can be conveyed by a frequency histogram.

5
STAT 211 Business Statistics I – Term 062, Major 1

Question Two (5 pts):
A set of 60 observations has a mean of 66.8 and a standard deviation of 3.55, if the
distribution is symmetric and has bell shape, approximately how many
observations should be found in the interval 59.7 and 73.9?

Question Three (5 pts):
Incomes in a particular market area are known to be right-skewed with a mean
equal to \$33,100. In a report issued recently, a manager stated that at least 88
percent of all incomes are in the range of \$26,700 to \$39,500, what is the standard
deviation for the incomes in this market area?

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STAT 211 Business Statistics I – Term 062, Major 1

Question Four (5+5 pts):
Bassart Electronics is considering employing one of two training programs. Two
groups were trained for the same task. Group 1 was trained by program A; group
2, by program B. for the first group, the times required to train the employees had
the average 32.11 hours and variance 68.09. In the second group, the average was
28.75 hours and the variance was 123.21.
a. Which training program has less relative variability in its performance?
Explain.

b. If two employees, one from each group, needed 50 training hours, which
employee is closer to an average employee in his group? Explain.

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STAT 211 Business Statistics I – Term 062, Major 1

Question Five (5+2+6+9 pts):
Farm stores compares prices charged for identical items in all of its food stores.
Here are the prices (in SR) charged by each store for a kg of meat

31.4 28.5 31.7 36.0 38.6 33.1 45.0 31.4 35.4 30.5

Given that  xi  341.6 and  xi 2  11879.04
a. Calculate the sample mean price per kg and the sample median price per kg.

b. Which value is better measure of the central tendency of these data? Explain

c. Calculate the sample standard deviation and the coefficient of variation and
comment of the variation of the data.

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STAT 211 Business Statistics I – Term 062, Major 1

d. Construct a box and whisker plot, and comment on the shape.

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