Mathematics
Average / Arithmetic Mean
A group of 19 people has average 43. Two people aged 32 and 37 leave, and two aged 52 and 57 join. What is the new average?
A. 47.11
B. 46.11
C. 45.11
D. 44.11
Correct Answer: C
Adjust the unchanged-size group's total, then divide by 19. New mean = 45.11.
Mathematics
Average / Arithmetic Mean
A group of 18 people has average 42. Two people aged 31 and 36 leave, and two aged 51 and 56 join. What is the new average?
A. 43.22
B. 45.22
C. 46.22
D. 44.22
Correct Answer: D
Adjust the unchanged-size group's total, then divide by 18. New mean = 44.22.
Mathematics
Average / Arithmetic Mean
A group of 17 people has average 41. Two people aged 30 and 35 leave, and two aged 50 and 55 join. What is the new average?
A. 43.35
B. 42.35
C. 44.35
D. 45.35
Correct Answer: A
Adjust the unchanged-size group's total, then divide by 17. New mean = 43.35.
Mathematics
Average / Arithmetic Mean
A group of 16 people has average 40. Two people aged 29 and 34 leave, and two aged 49 and 54 join. What is the new average?
A. 43.5
B. 42.5
C. 44.5
D. 41.5
Correct Answer: B
Adjust the unchanged-size group's total, then divide by 16. New mean = 42.5.
Mathematics
Average / Arithmetic Mean
A group of 15 people has average 39. Two people aged 28 and 33 leave, and two aged 48 and 53 join. What is the new average?
A. 42.67
B. 41.67
C. 43.67
D. 40.67
Correct Answer: B
Adjust the unchanged-size group's total, then divide by 15. New mean = 41.67.
Mathematics
Average / Arithmetic Mean
A group of 14 people has average 38. Two people aged 27 and 32 leave, and two aged 47 and 52 join. What is the new average?
A. 39.86
B. 41.86
C. 40.86
D. 42.86
Correct Answer: C
Adjust the unchanged-size group's total, then divide by 14. New mean = 40.86.
Mathematics
Average / Arithmetic Mean
A group of 13 people has average 37. Two people aged 26 and 31 leave, and two aged 46 and 51 join. What is the new average?
A. 39.08
B. 42.08
C. 41.08
D. 40.08
Correct Answer: D
Adjust the unchanged-size group's total, then divide by 13. New mean = 40.08.
Mathematics
Average / Arithmetic Mean
A group of 12 people has average 36. Two people aged 25 and 30 leave, and two aged 45 and 50 join. What is the new average?
A. 39.33
B. 41.33
C. 38.33
D. 40.33
Correct Answer: A
Adjust the unchanged-size group's total, then divide by 12. New mean = 39.33.
Mathematics
Average / Arithmetic Mean
The mean of 29 observations was reported as 59. One observation was recorded as 83 instead of 75. Find the corrected mean.
A. 58.72
B. 59.72
C. 59.22
D. 58.22
Correct Answer: A
Corrected mean = 59+(75−83)/29 = 58.72.
Mathematics
Average / Arithmetic Mean
The mean of 28 observations was reported as 58. One observation was recorded as 81 instead of 74. Find the corrected mean.
A. 57.75
B. 58.25
C. 57.25
D. 58.75
Correct Answer: A
Corrected mean = 58+(74−81)/28 = 57.75.
Mathematics
Average / Arithmetic Mean
The mean of 27 observations was reported as 57. One observation was recorded as 79 instead of 69. Find the corrected mean.
A. 57.63
B. 56.13
C. 56.63
D. 57.13
Correct Answer: C
Corrected mean = 57+(69−79)/27 = 56.63.
Mathematics
Average / Arithmetic Mean
The mean of 26 observations was reported as 56. One observation was recorded as 77 instead of 68. Find the corrected mean.
A. 55.15
B. 55.65
C. 56.15
D. 56.65
Correct Answer: B
Corrected mean = 56+(68−77)/26 = 55.65.
Mathematics
Average / Arithmetic Mean
The mean of 25 observations was reported as 55. One observation was recorded as 75 instead of 67. Find the corrected mean.
A. 55.18
B. 54.68
C. 54.18
D. 55.68
Correct Answer: B
Corrected mean = 55+(67−75)/25 = 54.68.
Mathematics
Average / Arithmetic Mean
The mean of 24 observations was reported as 54. One observation was recorded as 73 instead of 66. Find the corrected mean.
A. 54.21
B. 53.71
C. 54.71
D. 53.21
Correct Answer: B
Corrected mean = 54+(66−73)/24 = 53.71.
Mathematics
Average / Arithmetic Mean
The mean of 23 observations was reported as 53. One observation was recorded as 71 instead of 61. Find the corrected mean.
A. 52.57
B. 53.57
C. 52.07
D. 53.07
Correct Answer: A
Corrected mean = 53+(61−71)/23 = 52.57.
Mathematics
Average / Arithmetic Mean
The mean of 22 observations was reported as 52. One observation was recorded as 69 instead of 60. Find the corrected mean.
A. 52.09
B. 51.09
C. 52.59
D. 51.59
Correct Answer: D
Corrected mean = 52+(60−69)/22 = 51.59.
Mathematics
Average / Arithmetic Mean
The mean of 21 observations was reported as 51. One observation was recorded as 67 instead of 59. Find the corrected mean.
A. 50.12
B. 51.62
C. 51.12
D. 50.62
Correct Answer: D
Corrected mean = 51+(59−67)/21 = 50.62.
Mathematics
Average / Arithmetic Mean
The mean of 20 observations was reported as 50. One observation was recorded as 65 instead of 58. Find the corrected mean.
A. 50.65
B. 49.15
C. 50.15
D. 49.65
Correct Answer: D
Corrected mean = 50+(58−65)/20 = 49.65.
Mathematics
Average / Arithmetic Mean
The combined average of two classes is 51.14. Class A has 24 students averaging 48. Class B has 11 students. What is Class B's average?
A. 58
B. 56
C. 60
D. 62
Correct Answer: A
Class B mean = (combined total − Class A total)/11 = 58.
Mathematics
Average / Arithmetic Mean
Class A has 23 students averaging 46 marks and Class B has 10 students averaging 57. What is the overall average?
A. 51.33
B. 53.33
C. 49.33
D. 47.33
Correct Answer: C
Overall mean = (23×46+10×57)/33 = 49.33.