Exam 2: Describing Data: Numerical

The sample covariance may never be negative.

Which of the following represents a disadvantage of using the sample range to measure spread or dispersion?

THE NEXT QUESTIONS ARE BASED ON THE FOLLOWING INFORMATION: The following data represents the number of minutes an athlete spends training per day. The mean and standard deviation were computed to be 85.54 and 6.97,respectively.The median is 85.5 -What percentage of measurements would you expect to be between 71.60 and 99.48?

THE NEXT QUESTIONS ARE BASED ON THE FOLLOWING INFORMATION: Consider the following observations on shear strength of a joint bonded in a particular manner: -Determine the value of the sample mean.

For any set of numerical data values arranged in an ascending or descending order,the value of the observation in the center is called the weighted mean.

A researcher interested in determining the average monthly expenditures of college students on DVDs finds that for a sample of 25 students,the mean expenditure was $24.40,and the median expenditure was $21.76.Specify the shape of the histogram for this data.Does this shape make sense? Why?

If the mean of a quantitative data set exceeds the median,the data are considered to be symmetrical.

THE NEXT QUESTIONS ARE BASED ON THE FOLLOWING INFORMATION: Consider the following scores on a 20 point aptitude test for two samples of eight students each: Sample 1: 18,19,17,15,14,20,14,and 16 Sample 2: 14,15,13,11,10,16,10,and 12 -Calculate the mean score in sample 2.

From the data presented above,calculate the interquartile range.

What is the relationship among the mean,median,and mode in a symmetrical distribution?

When extreme values are present in a set of data,which pair of the following descriptive summary measures of central tendency and dispersion is most appropriate?

THE NEXT QUESTIONS ARE BASED ON THE FOLLOWING INFORMATION: Chebyshev's theorem is used to approximate the proportion of observations for any data set,regardless of the shape of the distribution.Assume that a distribution has a mean of 255 and standard deviation of 20. -Approximately what proportion of the observations is between 215 and 295?

THE NEXT QUESTIONS ARE BASED ON THE FOLLOWING INFORMATION: A sample of 33 students was 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: -Calculate the median.

THE NEXT QUESTIONS ARE BASED ON THE FOLLOWING INFORMATION: An investment councilor recently reviewed the account activity of a sample of 10 of his clients and calculated the average number of stock trades per month over the past year for each client.He obtained the following data values: 10.2,2.5,11.4,3.2,1.1,3.4,8.4,9.7,11.2,and 2.4 -Calculate the median number of trades per month for these 10 clients.

THE NEXT QUESTIONS ARE BASED ON THE FOLLOWING INFORMATION: The following data represent scores on a 15 point aptitude test: 8,10,15,12,14,and 13. -Subtract 5 from every observation and compute the sample mean for the original data and the new data.

The coefficient of variation measures variability in a positively skewed data set relative to the size of the median.

One possible source of skewness is the presence of outliers,and sometimes skewness is simply inherent in the distribution.

The mean is a better measure of central tendency than the median when there are outliers.

Measures of central tendency provide numerical information about a "typical" observation in the data.

For salaries of $108,000,$102,000,$52,000,$105,000,107,000 and $101,000,the arithmetic mean would be an appropriate measure of central tendency.