Exam 3: Numerical Descriptive Techniques

Ages of Jockeys: The following data represent the ages in years of a sample of 25 jockeys from a local race track: 31, 43, 56, 23, 49, 42, 33, 61, 44, 28, 48, 38, 44, 35, 40, 64, 52, 42, 47, 39, 53, 27, 36, 35, and 20. -Find the upper quartile of the ages.

In a perfectly symmetric bell shaped "normal" distribution:

Test Scores: Suppose that an analysis of a set of test scores reveals that: Q₁ = 45, Q₂ = 85, Q₃ = 105. -What do these statistics tell you about the shape of the distribution of test scores?

If , , n = 12, and the slope equals 0.5, then the y-intercept of the least squares line is b₀ = 276.08.

Suppose a sample of size 50 has a sample mean of 20. In this case, the sum of all observations in the sample is 1,000.

If a data set contains an even number of observations, the median is found by taking the ____________________ of these two numbers.

The ____________________ is not as sensitive to extreme values as the ____________________.

The smaller the spread of scores around the mean:

Expressed in percentiles, the interquartile range is the difference between the 25^th and 75^th percentiles.

Which is a better measure of variability in the weights of the workers, the standard deviation or the coefficient of variation?

Salaries of Employees: The following data represent the yearly salaries (in thousands of dollars) of a sample of 13 employees of a firm: 26.5, 23.5, 29.7, 24.8, 21.1, 24.3, 20.4, 22.7, 27.2, 23.7, 24.1, 24.8, and 28.2. -Compute the mean salary.

Which of the following summary measures cannot be easily approximated from a box plot?

Longevity and Salary: A sample of eight observations of variables x (years of experience) and y (salary in $1,000s) is shown below: -Determine the least squares line, and use it to estimate the value of y for x = 6.

Hours of Playing Video Games: Suppose that the following data provide the hours of playing video games per week for a sample of 15 high school students in Roanoke, Virginia: 5, 11, 25, 19, 18, 20, 27, 13, 8, 10, 15, 19, 18, 9, and 12. -Determine the location and value of the first quartile.

The following data represent the salaries (in thousands of dollars) of a sample of 13 office workers of a firm: 26.5, 23.5, 29.7, 24.8, 21.1, 24.3, 20.4, 22.7, 27.2, 23.7, 24.1, 24.8, and 28.2. -Compute the range.

The variance is more meaningful and easier to interpret compared to the standard deviation.

Which of the following summary measures is affected most by extreme values?

The ____________________ of a linear relationship is hard to interpret from the covariance, but it is easy to interpret from the correlation.

Three measures of the linear relationship between x and y are the coefficient of correlation, the coefficient of determination, and the coefficient of variation.

A sample of 12 construction workers has a mean age of 25 years. Suppose that the sample is enlarged to 14 construction workers, by including two additional workers having common age of 25 each. Find the mean of the sample of 14 workers.