108. Numerical Measures of Variability for Ungrouped Data
1. A sample of 10 students was asked by the instructor to record the number of hours each spent studying for a given exam from the time the exam was announced in class. The following data values were the recorded numbers of hours: 12, 15, 8, 9, 14, 8, 17, 14, 8, and 15.
The variance for the number of hours spent studying for this sample is
(a) 10.0000.
(b) 9.0000.
(c) 3.4641.
(d) approximately 12.
2. The numbers of minutes spent in the computer lab by 20 students working on a project are given below:
Numbers of Minutes
30 | 0, 2, 5, 5, 6, 6, 6, 8
40 | 0, 2, 2, 5, 7, 9
50 | 0,1, 3, 5
60 | 1, 3
The range for this data set is
(a) 300.
(b) 303.
(c) 603.
(d) 600.
3. The numbers of minutes spent in the computer lab by 20 students working on a project are given below:
Numbers of Minutes
30 | 0, 2, 5, 5, 6, 6, 6, 8
40 | 0, 2, 2, 5, 7, 9
50 | 0, 1, 3, 5
60 | 1, 3
The standard deviation for this data set is
(a) 101.6.
(b) 403.8.
(c) 306.0.
(d) 500.5.
4. The price increases on 5 stocks were $7, $1, $8, $4, and $5. The standard deviation for these price increases is
(a) 2.3.
(b) 2.7.
(c) 3.2.
(d) 4.1.
5. Which of the following is not affected by an extreme value in a data set?
The mean absolute deviation
The median
The range
The standard deviation
6. Given the following set of numbers 15, 20, 40, 25, 35. What is the variance?
(a) 9.27
(b) 86.0
(c) 10.37
(d) 107.5
7. Which of the following is the crudest measure of dispersion?
(a) The mean absolute deviation
(b) The variance
(c) The mode
(d) The range
8. Which of the following is not a measure of central tendency?
(a) Mean
(b) Median
(c) Q3
(d) Mode
9. Given the following data set: 12, 32, 45, 14, 24, and 31. The total deviation from the mean for the data values is
(a) 0.
(b) 26.3333.
(c) 29.5.
(d) 12.
10. Given that a sample is approximately bell-shaped with a mean of 60 and a standard deviation of 3, the approximate percentage of data values that is expected to fall between 54 and 66 is
(a) 75 percent.
(b) 95 percent.
(c) 68 percent.
(d) 99.7 percent.
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