Stat 4

What statistics are needed to draw a box plot?

Minimum, maximum, median, first and third quartiles

A sample of experienced typists revealed that their mean typing speed is 87 words per minute and the median is 73. The standard deviation is 16.9 words per minute. What is the Pearson's coefficient of skewness?

+2.5

What is the value of the Pearson coefficient of skewness for a distribution with a mean of 17, median of 12 and standard deviation of 6?

+2.5

A large oil company is studying the number of gallons of gasoline purchased per customer at self-service pumps. The mean number of gallons is 10.0 with a standard deviation of 3.0 gallons. The median is 10.75 gallons. What is the Pearson's coefficient of skewness?

-0.75

What is the possible range of values for the coefficient of variation?

0% and 100%

The test scores for a class of 147 students are computed. What is the location of the test score associated with the third quartile?

111

Mr. and Mrs. Jones live in a neighborhood where the mean family income is $45,000 with a standard deviation of $9,000. Mr. and Mrs. Smith live in a neighborhood where the mean is $100,000 and the standard deviation is $30,000. What is the relative dispersion of the family incomes in the two neighborhoods?

Jones 20%, Smith 30%

A large group of inductees was given a mechanical aptitude and a finger dexterity test. The arithmetic mean score on the mechanical aptitude test was 200, with a standard deviation of 10. The mean and standard deviation for the finger dexterity test were 30 and 6 respectively. What is the relative dispersion in the two groups?

Mechanical aptitude 5 percent, finger dexterity 20 percent

The coefficient of variation for a set of annual incomes is 18%; the coefficient of variation for the length of service with the company is 29%. What does this indicate?

More dispersion in the lengths of service compared with incomes

A study of the net sales of a sample of small corporations revealed that the mean net sales is $2.1 million, the median $2.4 million, the modal sales $2.6 million and the standard deviation of the distribution is $500,000. What is the Pearson's coefficient of skewness?

None of the above

A research analyst wants to compare the dispersion in the price-to-earnings ratios for a group of common stocks with their return on investment (ROI). For the price-to-earnings ratios, the mean is 10.9 and the standard deviation is 1.8. The mean return on investment is 25 percent and the standard deviation 5.2 percent. What is the relative dispersion for the price-to-earnings ratios and return on investment?

Price-to-earnings =16.5 percent, ROI = 20.8 percent

A study of business faculty at state supported institutions in Ohio revealed that the arithmetic mean salary for nine months is $52,000 and a standard deviation of $3,000. The study also showed that the faculty had been employed an average (arithmetic mean) of 15 years with a standard deviation of 4 years. How does the relative dispersion in the distribution of salaries compare with that of the lengths of service?

Salaries about 6%, service about 27%

A study of the scores on an in-plant course in management principles and the years of service of the employees enrolled in the course resulted in these statistics: - Mean test score was 200 with a standard deviation of 40 - Mean number of years of service was 20 years with a standard deviation of 2 years. In comparing the relative dispersion of the two distributions, what are the coefficients of variation?

Test 20%, service 10%

A dot plot shows

The general shape of a distribution

A row of a stem-and-leaf chart appears as follows: 3 | 0 1 3 5 7 9. Assume that the data is rounded to the nearest unit.

The maximum value in the class is 39

What does the interquartile range describe?

The middle 50% of the observations

A box plot shows

The relative symmetry of a distribution for a set of data

A student scored in the 85th percentile on a standardized test. This means that the student scored lower than 85% of all students who took the test.

false

The coefficient of variation is computed by dividing the standard deviation by the median and multiplying the quotient by 100.

false

A box plot shows the range of values that correspond to the upper 25% of the distribution

true

A box plot shows the relative symmetry of a distribution.

true

A percentile divides a distribution into one hundred equal parts.

true

For a distribution, the 2nd quartile, the 5th decile, and the 50th percentile, are the same as the median.

true

In a negatively skewed distribution, the mean is smaller than the median or mode and the mode occurs at the peak of the curve.

true

The Pearson's coefficient of skewness is a measure of distribution's symmetry

true

The coefficient of variation is a measure of relative dispersion that expresses the standard deviation as a percent of the mean.

true

The interquartile range is the difference between the values of the first and third quartile, indicating the range of the middle fifty percent of the observations

true

In a scatter diagram, we describe the relationship between

two variables measured at the interval or ratio level

In a contingency table, we describe the relationship between

two variables measured at the ordinal or nominal level.