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WorksheetsTopics 2-3: Descriptive statistics
Total questions: 20
Worksheet time: 15mins
Which of the following is a measure of data centrality?
Median
Z-score
Percentile
Standard deviation
Which of the following is a measure of data variability?
Mode
Quartile
Z-score
Range
Which of the following measures is NOT easily influenced by outliers in a data set?
Mean
Interquartile range
Variance
Correlation coefficient
Please find the median of the following data set:
1, 2, 3, 4, 5, 6, 7, 8
4
5
4.5
5.5
Which of the following statement is NOT true?
Median = Q2
50th percentile = Q2
IQR = Q1 - Q3
Range = Largest - Smallest
When a set of data is skewed to the right, we can say that ___.
the data set is postively skewed
the data set is negatively skewed
the mean is less than the median in most cases
the median and the mean are almost equal
Which of the following might be a proper estimate of the skewness of the data in the plot?
0
-0.5
0.8
0.2
What do we know about the a normally distributed population?
Approximately 68% of the data values fall within one standard deviation of the mean.
Approximately 95% of the data values fall within one standard deviation of the mean.
Approximately all of the data values fall within two standard deviations of the mean.
Approximately 95% of the data values fall within three standard deviations of the mean.
Suppose the mean value of people's IQ is 100 and the standard deviation is 10, what is the z-score of an individual whose IQ score is 120?
-1
-2
1
2
When using the rule of 1.5*IQR to detect outliers of a data set, what is the upper limit?
Q1 + 1.5*IQR
Q1 - 1.5*IQR
Q3 + 1.5*IQR
Q3 - I.5*IQR
Which of the following boxplot corresponds to this histogram?
None of the above
Consider the three scatterplots. Which has the greatest correlation coefficient?
I
II
III
The all have the same correlation coefficient.
This question cannot be answered without additional information.
To which of the following boxplots does the histogram correspond?
The graph shows household income in Laguna Woods, California. What can be said about the ratio median family incomemean family income ?
Approximately zero.
Less than one, but definitely above zero.
Approximately one.
Greater than one.
Suppose the average score on a national test is 500 with a standard deviation of 100. If each score is increased by 25, what are the new mean and standard deviation?
500, 100
500, 125
525, 100
525, 125
If quartiles Q1 = 20 and Q3 = 30, which of the following must be true?
I. The median is 25.
II. The mean is between 20 and 30.
III. The standard deviation is at most 10.
I only
II only
III only
None are true
When a set of data has suspect outliers, which of the following are preferred measures of central tendency and of variability?
mean and standard deviation
mean and range
median and range
median and interquartile range
If the standard deviation of a set of observations is 0, you can conclude ___.
that the average value is 0
that all observations are the same value
that there is no relationship between the observations
none of the above
The graph below shows cumulative proportions
plotted against grade point averages for a large public high school. What is the median grade point average?
0.8
2.0
2.4
2.6
Consider the histogram of test scores. Which of the following is a true statement?
More students scored between 50 and 60 than between 90 and 100.
The mean score is probably less than the median score.
The middle (median) score was 75.
If the passing score was 60, most students failed.
