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Find the missing number when you know the mean

Year 8 maths · Fieldbook Learning

Name ______________________ Date __________

Find the total from the mean, then subtract the numbers you know.

  1. The mean of 5 numbers is 13. 4 of the numbers are 10, 13, 16, 14. What is the other number?
  2. The mean of 5 numbers is 19. 4 of the numbers are 21, 19, 22, 23. What is the other number?
  3. The mean of 5 numbers is 19. 4 of the numbers are 20, 17, 6, 29. What is the other number?
  4. The mean of 5 numbers is 18. 4 of the numbers are 20, 18, 20, 12. What is the other number?
  5. The mean of 6 numbers is 29. 5 of the numbers are 6, 28, 50, 28, 32. What is the other number?
  6. The mean of 6 numbers is 38. 5 of the numbers are 36, 9, 49, 41, 40. What is the other number?
  7. The mean of 6 numbers is 33. 5 of the numbers are 39, 46, 29, 27, 9. What is the other number?
  8. The mean of 6 numbers is 22. 5 of the numbers are 19, 14, 6, 30, 18. What is the other number?
  9. The mean of 7 numbers is 41. 6 of the numbers are 29, 26, 39, 75, 59, 23. What is the other number?
  10. The mean of 7 numbers is 40. 6 of the numbers are 44, 7, 73, 68, 17, 34. What is the other number?
  11. The mean of 7 numbers is 34. 6 of the numbers are 18, 41, 7, 57, 48, 26. What is the other number?
  12. The mean of 7 numbers is 33. 6 of the numbers are 13, 45, 54, 65, 8, 13. What is the other number?
  13. The mean of 8 numbers is 51. 7 of the numbers are 14, 40, 39, 69, 47, 85, 74. What is the other number?
  14. The mean of 8 numbers is 45. 7 of the numbers are 66, 10, 60, 73, 35, 17, 17. What is the other number?
  15. The mean of 8 numbers is 58. 7 of the numbers are 10, 48, 70, 83, 23, 86, 84. What is the other number?
  16. The mean of 8 numbers is 51. 7 of the numbers are 76, 64, 92, 27, 43, 26, 44. What is the other number?
  17. The mean of 9 numbers is 143. 8 of the numbers are 79, 181, 193, 145, 80, 150, 164, 131. What is the other number?
  18. The mean of 9 numbers is 141. 8 of the numbers are 132, 166, 181, 185, 178, 140, 101, 40. What is the other number?
  19. The mean of 9 numbers is 102. 8 of the numbers are 179, 85, 137, 151, 56, 174, 73, 61. What is the other number?
  20. The mean of 9 numbers is 110. 8 of the numbers are 150, 77, 73, 15, 139, 131, 186, 46. What is the other number?
More free practice: fieldbooklearning.com/uk/practice/year-8/find-the-missing-number-when-you-know-the-mean/

Play it as a quiz game

20 of these questions as multiple choice, with near-miss wrong answers, ready for Kahoot or Blooket.

  1. Download the game's own question template: in Kahoot, Add question → Import spreadsheet; in Blooket, Create a set → Spreadsheet import.
  2. Click the matching button below, then click the first empty question row of the template and paste.
  3. Save the template (Kahoot needs .xlsx, Blooket .csv) and upload it.
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Answer key: Find the missing number when you know the mean

  1. 12
  2. 10
  3. 23
  4. 20
  5. 30
  6. 53
  7. 48
  8. 45
  9. 36
  10. 37
  11. 41
  12. 33
  13. 40
  14. 82
  15. 60
  16. 36
  17. 164
  18. 146
  19. 2
  20. 173