Exam 4: A: Numerical Descriptive Techniques

In a positively skewed distribution,the percentage of data between the smallest observation and Q₁ is less than the percentage of data between Q₃ and the largest observation.

In a positively skewed distribution:

The units for the standard deviation are the same as the units for the original data (for example,feet,inches,etc. ).

The annual percentage rates of return over the past 10 years for two mutual funds are as shown below.Which fund would you classify as having the higher level of risk? Fund A: 7.1 -7.4 19.7 -3.9 32.4 41.7 23.2 4.0 1.9 29.3 Fund B: 10.8 -41 5.1 10.9 26.5 24.0 16.9 9.4 -2.6 10.1

Is it possible for the standard deviation of a data set to be larger than its variance? Explain.

Weights of Workers The following data represent the number of employees of a sample of 25 companies: 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. -The number of hours a college student spent studying during the final exam week was recorded as follows: 7,6,4,9,8,5,and 10.Compute $\bar { x }$ for the data and the value in an appropriate unit.

Which of the following is a measure of variability?

A sample of 13 college professors has a mean age of 30 years and a standard deviation of 5 years.Suppose that the sample is enlarged to 15 college professors,by including two additional professors that are each 30 years old.Will the standard deviation increase,decrease,or stay the same,and why?

The range is considered the weakest measure of variability.

The value of the standard deviation may be either positive or negative,while the value of the variance will always be positive.

Which of the following statements is true?

Which measure(s)of central location is/are meaningful when the data are ordinal?

The ____________________ is the square root of the ____________________.

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.

The number of hours a college student spent studying during the final exam week was recorded as follows: 7,6,4,9,8,5,and 10.Compute s² and s for the data and express the numbers in the appropriate unit.

Suppose that a firm's sales were $3,750,000 five years ago and are $5,250,000 today.What was the geometric mean growth rate in sales over the past five years?

Ages of Senior Citizens A sociologist recently conducted a survey of citizens 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 22 uninsured senior citizens were as follows: 65,66,67,68,69,70,71,73,74,75,76,77,78,79,80,81,86,87,91,92,94,and 97. -{Ages of Senior Citizens Narrative} Explain why there is no mode for this data set.

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.

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} What does the value of the first quartile tell you?

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