Homework answers / question archive / 1)The interquartile range is used as a measure of variability to overcome what difficulty of the range?         The heights of adult women are approximately normally distributed about a mean of 65 inches, with a standard deviation of 2 inches

1)The interquartile range is used as a measure of variability to overcome what difficulty of the range?         The heights of adult women are approximately normally distributed about a mean of 65 inches, with a standard deviation of 2 inches

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1)The interquartile range is used as a measure of variability to overcome what difficulty of the range?

 

 

 

 

2. The heights of adult women are approximately normally distributed about a mean of 65 inches, with a standard deviation of 2 inches. If Rachel is at the 95^th percentile in height for adult women, then her height, in inches, is closest to
3. The drying time of one particular paint is approximately normally distributed with a mean of 45 minutes. It is also known that 15% of walls painted with this paint need more than 55 minutes to dry completely. Find the standard deviation of this distribution.
4. The correlation coefficient ranges between
5. The Flight for Life emergency helicopter service is available for medical emergencies occurring 15 to 90 miles from the hospital. A long-term study of the service shows that the response time from receipt of the dispatch call to arrival at the scene of the emergency is normally distributed with standard deviation of 8 minutes. What is the mean response time (to the nearest whole minute) if only 6.7% of the calls require more than 54 minutes to respond?
6. A numerical value used as a summary measure for a sample, such as sample mean, is known as a
7. The sum of deviations of the individual data elements from their mean is
8. Suppose the correlation coefficient r_xy between amount of sleep (in hours) "x" and number of yawns made in 8AM classes "y", of 100 business statistics students is computed to be –0.82. Then
9. Which of the following would NOT be a correct interpretation of correlation coefficient of r = –0.89?
10. A student made scores of 85, 56, and 91 on her first three statistics tests. What does she need to make on her next test to have an 80 test average?
11. A sample of 99 distances has a mean of 24 feet and a median of 21.5 feet. Unfortunately, it has just been discovered that an observation which was erroneously recorded as "30" actually had a value of "35". If we make this correction to the data, then:
12. The numerical value of the standard deviation can never be
13. The measure of location which is the most likely to be influenced by extreme values in the data set is the
14. The p^th percentile is a value such that at least p percent of the observations are
15. Suppose we have the following data: 12, 17, 13, 25, 16, 21, 30, 14, 16, 18. 
    To find the 10% trimmed mean, what numbers should be deleted from the calculation?
16. The summary statistics for the hourly wages of a sample of 130 system analysts are given below.

Mean = 60

Range 20

Mode = 73

Variance = 324

Median = 74

The coefficient of variation equals

17. The American Veterinary Association claims that the annual cost of medical care for dogs averages $100 with standard deviation of $30, and for cats, annual cost averages $120 with standard deviation of $35. Assume that the annual veterinary expenses are independent and normally distributed. Suppose you have a dog and a cat. What is the probability that your annual cost will be within $50 of the mean?
18. Assuming the distribution is normally distributed with mean of 40 and standard deviation of 4, calculate the X values whose z scores are –1 and –1.5 respectively.  
19. The correlation coefficient between two scores X and Y equals 0.8. If both the X scores and the Y scores are converted to z-scores, then the correlation between the z-scores for X and the z-scores for Y would be
20. Consider these parallel boxplots of gasoline mileage for three makes of cars. Which of the following are true statements?

1. All three have the same range
2. All three have the same interquartile range
3. The difference in the medians between the first and third distributions is equal to the interquartile range of the second distribution

21. The interquartile range is
22. A doctor records for 400 hospital patients selected at random, note the pair of information: (temperature when admitted, temperature 24 hours later). He finds that the average patients' temperature upon admission is 101 degrees and 99 degrees 24 hours later. The standard deviation is 1.5 degrees for temperatures when admitted and 0.5 degrees for those the next day. The correlation between the two temperatures is 0.8. What so the covariance between the variables?
23. A data set has the following five-number summary: {31, 50, 58, 62, 87}. Which of the following pairs of values in this data set would be considered outliers?
24. In a five number summary, which of the following is not used for data summarization?
25. The standard deviation of a sample was reported to be 20. The report indicated that E (x-x(sub bar))^2 =7200. What is the sample size?
26. Which of the following is not resistant to the outliers in a data set?
27. The relative frequency of a class is computed by
28. Given the following information:

Standard deviation = 8 
Coefficient of variation = 64%

The mean is

29. Look at this boxplot. What can you tell about the data set it comes from?
30. Positive values of covariance indicate
31. A recent study found that hamburger fat calories "x" had a positive linear association with amount of sodium "y" found in that hamburger. This can be interpreted to indicate
32. If the variance of a data set is correctly computed with the formula using n – 1 in the denominator, which of the following is true?
33. The correlation coefficient is

 

34. Which one of the following statistics measures both the strength and direction of a linear relationship?
35. Growth factors for the population of Dallas in the past five years have been 1, 2, 3, 4, and 5. The geometric mean is
36. When a set of data has suspect outliers, which of the following are preferred measures of central tendency and of variability?
37. Assuming the distribution is normally distributed with mean of 66 and standard deviation of 2, calculate the z-score for X = 68 and X = 69 respectively. 
38. Match the scatter plot to the description of its regression line and correlation coefficient.
39. A student was performing an experiment that compared a new high protein food to the old food for pigs. He found the mean weight gain for subjects consuming the new food to be 12.8 pounds with a standard deviation of 3.5 pounds. Later he realized that the scale was out of calibration by 1.5 pounds (meaning that the scale weighed items 1.5 pounds too much). What should the summary measures, mean and standard deviation, be for the subjects consuming the new food?
40. There are three executives in an office, ages 56, 57, and 58. If a 57-year-old executive enters the room, the
41. The difference between the largest and the smallest data values is the
42. In a sample of size five, the mean is 23 and four of the observations have the following deviations from the mean: –6, 2, 5, and 3. What is the value of the fifth observation?
43. Which of the following provides a measure of central location for the data?
44. The coefficient of variation is
45. In a sample of 500 students whose mean height is 67.8 inches, 150 were women. If the mean height of the women was 63.0 inches, what is the mean height of the men in the sample?
46. When data are positively skewed, the mean will usually be

 

47. When testing water for chemical impurities, results are often reported as BDL, that is, below detection limit. The following data set gives the measurements of the amount of lead in a series of water samples taken from inner-city households (ppm):

5,7,12,BDL,10,8,BDL,20,6

Which of the following is correct?

48. A numerical measure of linear association between two variables is the
49. The following is a histogram showing the actual frequency of the average college professor salary from 50 randomly selected colleges. Based on the frequency histogram for salaries, the bin that contains the 80^th percentile is

Quiz 3A

1. Chapter 3 focuses on
2. The company identified in chapter 3, statistics in practice is
3. The statistics in practice example in chapter 3 concerned
4. Consider the attached student data. What is the mean of friends? E
5. Consider the data. What is the median of friends?

Quiz 3B

1. Consider the attached student data. What is the range of friends
2. Consider the Student Data. What is the interquartile range of Friends?  Enter your answer rounded to two decimal places.
3. Consider the Student Data. What is the sample standard deviation of Friends?  Enter your answer rounded to two decimal places.
4. 
   Consider the Student Data. What is the coefficient of variation of Friends?  Enter your answer as a percent rounded to two decimal places and without a percent sign.
5. Consider the Student Data. What is the value of skewness of Friends?  Enter your answer rounded to two decimal places.

Quiz 3C

1. An unusually small or unusually large data value is called

 

2. A box plot is a graphical representation of data that is based on
3. Consider the attached data, what is the correlation between SAT Verbal and SAT Math?  Enter your answer rounded to three decimal places.
4. Functionality in interactive data dashboards that allows the user to access information and analyses at an increasingly detailed level is referred to as