Exam 4: Numerical Descriptive Techniques

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.

The ____________________ of the correlation indicates the direction of a linear relationship.

Hours Worked per Week ​ The following data represent the hours worked per week of a sample of 25 employees from a government department: 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. ​ ​ -{Hours Worked per Week Narrative} Find the median hours.

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. ​ ​ -{Ages of Jockeys Narrative} Compute the interquartile range of the data and interpret its meaning.

Quartiles divide the observations in a data set into four parts with the same amount of data in each part.

Ages of Retirees ​ A sociologist recently conducted a survey of retirees over 65 years of age whose net worth is too high to qualify for Medicaid and who have no private health insurance.The ages of 20 uninsured retirees were as follows: 65,66,67,68,69,70,71,73,74,75,78,79,80,81,86,87,91,92,94,and 97. ​ ​ -{Ages of Retirees Narrative} Describe the shape of the distribution of ages by comparing the quartiles.

____________________ uses both the mean and the standard deviation to interpret standard deviation for histograms of any shape.

Pets Survey A sample of 36 families were asked how many pets they owned.Their responses are summarized in the following table. ​ ​ -{Pets Survey Narrative} Determine the mean,the median,and the mode of the number of pets owned per family.

In a histogram,the proportion of the total area which must be to the left of the median is less than 0.50 if the distribution is negatively skewed.

The interquartile range is an interval of numbers starting at Q₁ and ending at Q₃.

Ages of Retirees ​ A sociologist recently conducted a survey of retirees over 65 years of age whose net worth is too high to qualify for Medicaid and who have no private health insurance.The ages of 20 uninsured retirees were as follows: 65,66,67,68,69,70,71,73,74,75,78,79,80,81,86,87,91,92,94,and 97. ​ ​ -{Ages of Retirees Narrative} Calculate the first quartile of the ages of the uninsured retirees.

In a histogram,the proportion of the total area which must be to the right of the mean is:

Strip Mall Rent ​ Monthly rent data in dollars for a sample of 10 stores in a small town in South Dakota are as follows: 220,216,220,205,210,240,195,235,204,and 250. ​ ​ -{Strip Mall Rent Narrative} What is the mode?

If the coefficient of correlation r = −.81,the standard deviations of x and y are 20 and 25,respectively,then cov(x,y)must be −405.0.

The Empirical Rule states that the approximate percentage of measurements in a data set (providing that the data set has a bell shaped distribution)that fall within two standard deviations of their mean is approximately:

Which of the following is correct about the shape of a distribution?

The middle line inside the box in a box plot represents the ____________________.

The horizontal lines extending to the left and to the right of the box in a box plot are called ____________________.

The strength of the linear relationship between two interval variables can be measured by the:

Yearly Donations ​ The following data represent the yearly donations (in thousands of dollars)of a sample of 13 benefactors: 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. ​ ​ -{Yearly Donations Narrative} Compute the upper quartile.