Exam 3: Numerical Descriptive Techniques

The ____________________ is the square root of the ____________________.

The coefficient of correlation r is a number that indicates the direction and the strength of the linear relationship between the dependent variable y and the independent variable x .

If , , n = 12, and the slope equals 0.5, then the y -intercept of the least squares line is b ₀ = 276.08.

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. {Hours of Playing Video Games Narrative} Determine the location and value of the third quartile.

Salaries of Office Workers 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. {Salaries of Office Workers Narrative} Compute the coefficient of variation, and express the number in the appropriate unit.

There are three measures of central location; the mean, the ____________________ and the ____________________.

Milk Demand A supermarket has determined that daily demand for milk containers has an approximate bell shaped distribution, with a mean of 55 containers and a standard deviation of six containers. {Milk Demand Narrative} If the supermarket begins each morning with a supply of 67 containers of milk, how often will demand exceed the supply? (Give a percentage.)

According to the Empirical Rule, if the data form a bell shaped normal distribution approximately ____________________ percent of the observations will be contained within 1 standard deviation around the mean.

If the first and second quartiles are closer to each other than are the second and third quartiles, the shape of the histogram based on the quartiles is ____________________.

Percentiles can be converted into quintiles and deciles, where quintiles divide the data into fifths and deciles divide the data into tenths.

Lily has been keeping track of what she spends to eat out. The last week's expenditures for meals eaten out were $5.69, $5.95, $6.19, $10.91, $7.49, $14.53, and $7.66. The mean amount Lily spends on meals is $8.35.

If the coefficient of correlation r = ± 1, then the best-fit linear equation will actually include all of the observations.

Which of the following summary measures is sensitive to extreme values?

Ages of Volunteers The following data represent the ages in years of a sample of 25 volunteers from a charitable organization: 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. {Ages of Volunteers Narrative} Compute the sample variance, and sample standard deviation, and express the numbers in the appropriate units.

The interquartile range is the difference between the:

A sample of 20 observations has a standard deviation of 3. The sum of the squared deviations from the sample mean is:

Weights of Police Officers The following data represent the weights in pounds of a sample of 25 police officers: 164, 148, 137, 157, 173, 156, 177, 172, 169, 165, 145, 168, 163, 162, 174, 152, 156, 168, 154, 151, 174, 146, 134, 140, and 171. {Weights of Police Officers Narrative} Construct a relative frequency histogram for the data, using five class intervals and the value 130 as the lower limit of the first class.

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. {Salaries of Employees Narrative} Compute the median salary.

The ____________________ is the least effective of all the measures of variability.

The ____________________ measures the spread between the middle 50% of the observations.