The interquartile range (IQR) is a number that indicates the spread of what part of the data?

Correct answer: The middle 50 percent of the data.

Explanation

This question tests the definition and interpretation of the Interquartile Range (IQR), a key measure of statistical dispersion.

Other questions

Question 1

In a stem-and-leaf plot, what does the 'leaf' typically consist of?

Question 2

What is an observation of data that does not fit the rest of the data often called?

Question 3

According to the textbook, what is a primary difference between a histogram and a bar graph?

Question 4

What are the common measures of the location of data discussed in the chapter?

Question 6

For the following 13 real estate prices, what is the Interquartile Range (IQR)? Prices are: 389,950; 230,500; 158,000; 479,000; 639,000; 114,950; 5,500,000; 387,000; 659,000; 529,000; 575,000; 488,800; 1,095,000.

Question 7

When is the median generally a better measure of the center of the data than the mean?

Question 8

In a small town of 50 people, one person earns 5,000,000 dollars per year and the other 49 each earn 30,000 dollars. Which is the better measure of the 'center'?

Question 9

What is the most frequent value in a data set called?

Question 10

The distribution of a dataset is described as being 'chopped off' on the right-hand side compared to the left side. What is this type of distribution called?

Question 11

In a perfectly symmetrical distribution, what is the relationship between the mean and the median?

Question 12

What does the standard deviation measure?

Question 13

If a dataset has a standard deviation of zero, what can be concluded about the data values?

Question 14

In the context of the sample standard deviation formula, why is the denominator n - 1 used instead of n?

Question 15

In a survey of 40 parents about how many times a week a teenager must be reminded to do chores, the results included '3 times' with a frequency of 14. What is the relative frequency of this response?

Question 16

Which of the following is a characteristic of a probability density function (PDF) for a random variable?

Question 17

What is the formula for the geometric mean?

Question 18

For which of the following scenarios is the geometric mean most relevant?

Question 19

What is the geometric mean of the numbers 5, 10, and 20?

Question 20

The formula for variance is the average of the...

Question 21

For the Park City basketball team, with scores 32, 32, 33, 34, 38, what is the correct representation in a stem-and-leaf plot?

Question 22

What is the median for the data set of test scores: 50, 53, 59, 59, 63, 63, 72, 72, 72, 72, 72, 76, 78, 81, 83, 84, 84, 84, 90, 93?

Question 23

According to the Empirical Rule for a bell-shaped distribution, approximately what percentage of data is within one standard deviation of the mean?

Question 24

A z-score represents the number of ______ a data value is from its mean.

Question 25

In Example 2.32, John's GPA is 2.85 with a school mean of 3.0 and standard deviation of 0.7. Ali's GPA is 77 with a school mean of 80 and standard deviation of 10. Who has the better GPA when compared to their respective school?

Question 26

For the test scores for a college statistics class held during the day in Example 2.15, what is the interquartile range (IQR)?

Question 27

Using the 1.5 times IQR rule on the night class data from Example 2.15, what is the lower boundary for identifying outliers?

Question 28

In the sleep study data from Table 2.24, what is the 28th percentile for hours of sleep?

Question 29

Using the formula for finding the kth percentile from Example 2.17, what is the 70th percentile for the 29 ages of Academy Award winners?

Question 30

What does a z-score of -1.5 for a test score mean?

Question 31

In a distribution that is skewed to the right, which measure of central tendency is typically the largest?

Question 32

What is the primary purpose of the Coefficient of Variation?

Question 33

A statistics professor collects information on the classification of her students (first-year, sophomore, junior, senior) and displays it in a pie chart. What type of data is being shown?

Question 34

A histogram summarizes the number of credit hours students complete. The class boundaries are 10 to less than 13, 13 to less than 16, and so on. What type of data does this graph show?

Question 35

What is the key feature of a Pareto chart?

Question 36

The calculation for the mean of a grouped frequency table involves multiplying the frequency of each interval by what value?

Question 37

For the data set 4, 5, 6, 6, 6, 7, 7, 7, 7, 7, 7, 8, 8, 8, 9, 10, what are the mean, median, and mode?

Question 38

When creating a histogram for discrete data where values are integers like 1, 2, 3, etc., what is a convenient starting point for the first interval?

Question 39

In a survey of 40 people who had their car in the shop for repairs, 7 people had 0 repairs, 10 had 1 repair, 14 had 2 repairs, and 9 had 3 repairs. What is the mean number of repairs?

Question 40

What does the Greek letter mu (μ) represent in statistics?

Question 41

A value is suspected to be a potential outlier if it is less than what value, according to the rule provided in the textbook?

Question 42

What is the formula for the sample mean, x-bar?

Question 43

On a timed math test, the first quartile for time it took to finish the exam was 35 minutes. How should this be interpreted?

Question 44

In a right-skewed distribution, which measure of central tendency is most affected by the skewing?

Question 45

What is the key advantage of a histogram, according to the text?

Question 46

For the following dataset of ages for Academy Award winners, what is the percentile for the age 58? Data: 18; 21; 22; 25; 26; 27; 29; 30; 31; 33; 36; 37; 41; 42; 47; 52; 55; 57; 58; 62; 64; 67; 69; 71; 72; 73; 74; 76; 77.

Question 47

What is the best estimate for the class mean given the grade intervals and student numbers in Table 2.26?

Question 48

If a distribution has two modes, it is called:

Question 49

The sample standard deviation for the ages of 20 fifth-grade students in Example 2.29 was calculated to be approximately 0.72. A data value of 11.5 is how many deviations from the mean (10.53)?

Question 50

The Key Terms section defines 'Variance' as the mean of the...