1. A variable is a characteristic that changes or varies over time, and/or for different individuals or
objects under consideration. An experimental unit is the individual or object on which a variable
2. Bar and pie charts are graphical techniques for qualitative data. The former focus the attention on
the frequency of the occurrences of the categories, and the later emphasize the percentage of
occurrences of each category.
3. Individual observations within each class may be found in a frequency distribution.
4. Compared to the frequency distribution, the stem-and-leaf plot provides more details, since it can
describe the individual data values as well as show how many are in each group, or stem.
5. A relative frequency distribution describes the proportion of data values that fall within each
6. When data have been grouped (as in a frequency table, a relative frequency histogram, etc.), the
class with the highest frequency is called the modal class, and the midpoint of that class is taken
to be the mode.
7. Jessica has been keeping track of what she spends to eat out. The last week's expenditures for
meals eaten out were $15.69, $15.95, $16.19, $20.91, $17.49, $24.53, and $17.66. The mean
amount Jessica spends on meals is $18.35.
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8. The Empirical Rule states that: Given a distribution of measurements that is approximately bell-
shaped (mound-shaped), the interval contains approximately 68% of the measurements,
the interval contains approximately 95% of the measurements, and the interval
contains all or almost all of the measurements.
9. The distribution of checking account balances for customers at Independent Bank is known to be
bell – shaped with a mean of $1,800 and a standard deviation of $300. Given this information, the
percentage of accounts with balances between $1,500 and $2,100 will be approximately 95%.
10. The distribution of credit card balances for customers is highly skewed to the right with a mean of
$1,200 and a standard deviation of $150. Based on this information, approximately 68% of the
customers will have credit card balances between $1,050 and $1,350.
11. Which measure of center is meaningful when the data are qualitative?
a. the mean
b. the median
c. the mode
d. all of the these
e. none of these
12. Which of the following statements is true for the following data values: 17, 15, 16, 14, 17, 18,
a. The mean, median and mode are all equal.
b. Only the mean and median are equal.
c. Only the mean and mode are equal.
d. Only the median and mode are equal.
e. The mean, median and mode are all different.
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13. A random sample from an unknown population had a sample standard deviation of zero. Which
one of the following is a reasonable conclusion?
a. The sample range must be zero.
b. An error was made in computing the sample standard deviation. It must always be
greater than zero.
c. The population standard deviation must be zero.
d. The population standard deviation must be zero when the mean is zero.
e. None of these.
14. Which of the following statements about the median is correct?
a. It is a measure of center that divides an ordered array of data into two halves.
b. If data are arranged in ascending order from smallest to largest, all the
observations below the median are smaller than or equal to it, while all the
observations above the median are equal to it or larger.
c. If the total number of observations is odd, the median is the middle observation in
an ordered array; if the total number of observations is even, the median is the
average of the two middle values.
d. All of these.
e. None of these.
15. Which of the following represents a disadvantage of using the sample range to measure spread
a. It produces spreads that are too large.
b. The sample range is not measured in the same units as the data.
c. The largest or smallest observation (or both) may be an outlier.
d. None of these is correct.
e. All of these are correct.