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2.5 Measures of the Center of the Data

Mean, median and mode computed from raw lists and from grouped frequency tables, plus the sampling variability that makes one sample's average differ from another's.

Introductory Statistics 2e, 2.5 Measures of the Center of the Data

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10 exercises

2.5 Exercise 1

A hospital administrator keeps track of the ages (in years) of patients visiting the emergency room over a one-week period (data are sorted from smallest to largest):
3; 4; 8; 8; 10; 11; 12; 13; 14; 15; 15; 16; 16; 17; 17; 18; 21; 22; 22; 24; 24; 25; 26; 26; 27; 27; 29; 29; 31; 32; 33; 33; 34; 34; 35; 37; 40; 44; 44; 47;
Calculate the mean and the median.

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2.5 Exercise 3

Suppose that in a small town of 50 people, one person earns $5,000,000 per year and the other 49 each earn $30,000. Which is the better measure of the "center": the mean or the median?

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2.5 Exercise 5

  1. 50
  2. 53
  3. 59
  4. 59
  5. 63
  6. 63
  7. 72
  8. 72
  9. 72
  10. 72
  11. 72
  12. 76
  13. 78
  14. 81
  15. 83
  16. 84
  17. 84
  18. 84
  19. 90
  20. 93

Find the mode.

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2.5 Exercise 8

A frequency table displaying professor Blount’s last statistic test is shown. Find the best estimate of the class mean.

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2.5 Exercise 11

Use the following information to answer the next three exercises: The following data show the lengths of boats moored in a marina. The data are ordered from smallest to largest:

  1. 16
  2. 17
  3. 19
  4. 20
  5. 20
  6. 21
  7. 23
  8. 24
  9. 25
  10. 25
  11. 25
  12. 26
  13. 26
  14. 27
  15. 27
  16. 27
  17. 28
  18. 29
  19. 30
  20. 32
  21. 33
  22. 33
  23. 34
  24. 35
  25. 37
  26. 39
  27. 40

Calculate the mean.

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2.5 Exercise 13

Use the following information to answer the next three exercises: The following data show the lengths of boats moored in a marina. The data are ordered from smallest to largest:

  1. 16
  2. 17
  3. 19
  4. 20
  5. 20
  6. 21
  7. 23
  8. 24
  9. 25
  10. 25
  11. 25
  12. 26
  13. 26
  14. 27
  15. 27
  16. 27
  17. 28
  18. 29
  19. 30
  20. 32
  21. 33
  22. 33
  23. 34
  24. 35
  25. 37
  26. 39
  27. 40

Identify the mode.

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2.5 Exercise 15


Use the following information to answer the next three exercises: Sixty-five randomly selected car salespersons were asked the number of cars they generally sell in one week. Fourteen people answered that they generally sell three cars; nineteen generally sell four cars; twelve generally sell five cars; nine generally sell six cars; eleven generally sell seven cars. Calculate the following:

median…

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2.5 Exercise 18

the table gives the percent of children under five considered to be underweight. What is the best estimate for the mean percentage of underweight children?

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2.5 Exercise 20

What is the IQR?

  1. 8
  2. 11
  3. 15
  4. 35
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2.5 Exercise 22

Is this a sample or the entire population?

  1. sample
  2. entire population
  3. neither
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Adapted from Introductory Statistics 2e © 2023 Rice University. Licensed under CC BY 4.0. Source: Introductory Statistics 2e. Imported at revision 50ec917.