Stats Sp 2020- Chapter 4
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 Pearson's coefficient of skewness?
-3 and +3
In a scatter diagram, we describe the relationship between
two variables measured at the interval or ratio level.
In the following set of data, what are the first, second, and third quartiles? 1 3 5 6 7 9 100
3, 6, 9
Using the following statistics to describe a distribution of data, what is the interquartile range? Minimum = 10 Q1 = 25 Median = 50 Q3 = 75 Maximum = 95
50
A dot plot is best applied for a data set with
50 observations.
The interquartile range is graphically presented in a
Box plot.
A contingency table would be used to summarize data such as
Company employees by gender and organizational title.
A box plot graphically shows the 10th and 90th percentiles. T / F
False
A scatter diagram of sales versus production may be constructed by plotting the minimum, first quartile, median, third quartile, and the maximum values of each variable. T / F
False
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. T / F
False
Quartiles divide a distribution into ten equal parts. T / F
False
The coefficient of skewness is the standard deviation divided by the mean. T / F
False
In a distribution, the second quartile corresponds with the
Median
A stem-and-leaf display includes the following row: 5 | 10 11 31 52 79 98. Assume that the data is rounded to the nearest whole number.
The class interval is 100.
A dot plot can be used to show
The distribution for a quantitative variable.
A dot plot shows the
The general shape of a distribution.
What does the interquartile range describe?
The middle 50% of the observations
What statistics are needed to draw a box plot?
The minimum, maximum, median, first and third quartiles.
A dot plot is useful for quickly graphing frequencies in a small data set. T / F
True
A dot plot is useful for showing the range of the data. T / F
True
A relationship between two nominal variables is summarized by a contingency table. T / F
True
