Exam 2: Describing Data With Numerical Measures

A distribution of measurements is relatively mound-shaped, with mean 70 and standard deviation 10. a. What percentage of the measurements will fall between 60 and 80? b. What percentage of the measurements will fall between 50 and 90? c. What percentage of the measurements will fall between 50 and 80? d. If a measurement is chosen at random from this distribution, what is the probability that it will be greater than 80?

Aptitude Tests Twenty-eight applicants interested in working in community services took an examination designed to measure their aptitude for social work. A stem-and-leaf plot of the 28 scores appears below, in which the first column is the count per "branch," the second column is the stem value, and the remaining digits are the leaves. Count Stems Leaves 1 4 6 1 5 9 4 6 3688 6 7 026799 9 8 145667788 7 9 1234788 -Refer to Aptitude Tests table. What is the interquartile range?

Which of the following is a characteristic of a population mean?

Community College Raises Assume that all employees of a community college received a monthly raise. -Refer to the Community College Raises statement. What would happen to the mean of salaries if all salaries were raised by 5%? What would happen to the standard deviation of salaries if all salaries were raised by 4%?

Numerical descriptive measures computed from population measurements are called parameters.

Student Ratings Thirty-three students were asked to rate themselves on whether they were outgoing or not, using this five-point scale: 1 = extremely extroverted, 2 = extroverted, 3 = neither extroverted nor introverted, 4 = introverted, or 5 = extremely introverted. The results are shown in the table below: -Refer to Student Ratings table. Calculate the median.

If a set of data has 120 values, the value of the 30th percentile will be calculated using the 36th and 37th values in the data, when the data values have been arranged in ascending order.

If the 90th and 91st observations in a set of 100 data values are 158 and 167, respectively, what is the 90th percentile value?

Aptitude Tests Twenty-eight applicants interested in working in community services took an examination designed to measure their aptitude for social work. A stem-and-leaf plot of the 28 scores appears below, in which the first column is the count per "branch," the second column is the stem value, and the remaining digits are the leaves. Count Stems Leaves 1 4 6 1 5 9 4 6 3688 6 7 026799 9 8 145667788 7 9 1234788 -Suppose you are given the following set of sample measurements: -1, 0, 2, 6, 5, and 6. a. Calculate the sample mean. b. Find the median. c. Find the mode. d. Are these data symmetric, skewed to the right or skewed to the left? Justify your answer.

The following five-number summary for a sample of size 500 was obtained: Minimum = 250, and Maximum = 4,950. Based on this information, if you were to construct a box plot, the value corresponding to the right-hand edge of the box would be 4,800.

Which of the following can be used to summarize data about qualitative variables?

Psychological Experiments In a psychological experiment, the time on task was recorded for ten subjects having a five-minute time constraint. These measurements (in seconds) were 182, 197, 207, 272, 192, 257, 247, 197, 232, and 237. -Refer to the Psychological Experiments statement. Find the median time on task.

Psychological Experiments In a psychological experiment, the time on task was recorded for ten subjects having a five-minute time constraint. These measurements (in seconds) were 182, 197, 207, 272, 192, 257, 247, 197, 232, and 237. -Refer to the Psychological Experiments statement. Find the average time on task.

The Empirical Rule and Tchebysheff's Theorem can be used to describe data sets.

The value of the standard deviation will always exceed that of the variance.

The standard deviation is expressed in terms of the original units of measurement, but the variance is not.

If the distribution of sales is thought to be symmetric with very little variation, then what may one conclude about the box plot that represents the data set?

The Empirical Rule states the following: Given a distribution of measurements that is approximately bell-shaped (mound-shaped), then 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.

When the distribution is skewed to the right, the mean < the median.

A sample of n = 10 measurements consists of the following values: 15, 12, 13, 16, 11, 12, 14, 15, 11, and 13. Calculate the sample mean and the median of this data set. Are the data mound-shaped?