Mathematics
Average / Arithmetic Mean
A group of 15 people has average age 37. One person leaves and another aged 29 joins; the new average becomes 36. What was the age of the person who left?
A. 42 years
B. 46 years
C. 44 years
D. 48 years
Correct Answer: C
Old total + 29 − leaving age = 15×36; leaving age = 44.
Mathematics
Average / Arithmetic Mean
A group of 14 people has average age 36. One person leaves and another aged 28 joins; the new average becomes 35. What was the age of the person who left?
A. 44 years
B. 46 years
C. 42 years
D. 40 years
Correct Answer: C
Old total + 28 − leaving age = 14×35; leaving age = 42.
Mathematics
Average / Arithmetic Mean
A group of 13 people has average age 35. One person leaves and another aged 27 joins; the new average becomes 34. What was the age of the person who left?
A. 38 years
B. 42 years
C. 44 years
D. 40 years
Correct Answer: D
Old total + 27 − leaving age = 13×34; leaving age = 40.
Mathematics
Average / Arithmetic Mean
A group of 12 people has average age 34. One person leaves and another aged 26 joins; the new average becomes 33. What was the age of the person who left?
A. 36 years
B. 40 years
C. 42 years
D. 38 years
Correct Answer: D
Old total + 26 − leaving age = 12×33; leaving age = 38.
Mathematics
Average / Arithmetic Mean
A group of 11 people has average age 33. One person leaves and another aged 25 joins; the new average becomes 32. What was the age of the person who left?
A. 40 years
B. 36 years
C. 38 years
D. 34 years
Correct Answer: B
Old total + 25 − leaving age = 11×32; leaving age = 36.
Mathematics
Average / Arithmetic Mean
A group of 10 people has average age 32. One person leaves and another aged 24 joins; the new average becomes 31. What was the age of the person who left?
A. 32 years
B. 36 years
C. 34 years
D. 38 years
Correct Answer: C
Old total + 24 − leaving age = 10×31; leaving age = 34.
Mathematics
Average / Arithmetic Mean
A group of 9 people has average age 31. One person leaves and another aged 23 joins; the new average becomes 30. What was the age of the person who left?
A. 30 years
B. 34 years
C. 32 years
D. 36 years
Correct Answer: C
Old total + 23 − leaving age = 9×30; leaving age = 32.
Mathematics
Average / Arithmetic Mean
A group of 8 people has average age 30. One person leaves and another aged 22 joins; the new average becomes 29. What was the age of the person who left?
A. 28 years
B. 34 years
C. 32 years
D. 30 years
Correct Answer: D
Old total + 22 − leaving age = 8×29; leaving age = 30.
Mathematics
Average / Arithmetic Mean
A squad of 14 people has average age 36. A member aged 49 is replaced by one aged 29. Find the new average age.
A. 33.57 years
B. 34.57 years
C. 35.57 years
D. 36.57 years
Correct Answer: B
Total changes by -20; new mean = 34.57 years.
Mathematics
Average / Arithmetic Mean
A squad of 13 people has average age 35. A member aged 48 is replaced by one aged 28. Find the new average age.
A. 34.46 years
B. 32.46 years
C. 33.46 years
D. 35.46 years
Correct Answer: C
Total changes by -20; new mean = 33.46 years.
Mathematics
Average / Arithmetic Mean
A squad of 12 people has average age 34. A member aged 47 is replaced by one aged 27. Find the new average age.
A. 33.33 years
B. 31.33 years
C. 34.33 years
D. 32.33 years
Correct Answer: D
Total changes by -20; new mean = 32.33 years.
Mathematics
Average / Arithmetic Mean
A squad of 11 people has average age 33. A member aged 46 is replaced by one aged 26. Find the new average age.
A. 30.18 years
B. 33.18 years
C. 31.18 years
D. 32.18 years
Correct Answer: C
Total changes by -20; new mean = 31.18 years.
Mathematics
Average / Arithmetic Mean
A squad of 16 people has average age 32. A member aged 45 is replaced by one aged 25. Find the new average age.
A. 31.75 years
B. 32.75 years
C. 29.75 years
D. 30.75 years
Correct Answer: D
Total changes by -20; new mean = 30.75 years.
Mathematics
Average / Arithmetic Mean
A squad of 15 people has average age 31. A member aged 44 is replaced by one aged 24. Find the new average age.
A. 28.67 years
B. 31.67 years
C. 30.67 years
D. 29.67 years
Correct Answer: D
Total changes by -20; new mean = 29.67 years.
Mathematics
Average / Arithmetic Mean
A squad of 14 people has average age 30. A member aged 43 is replaced by one aged 23. Find the new average age.
A. 27.57 years
B. 28.57 years
C. 29.57 years
D. 30.57 years
Correct Answer: B
Total changes by -20; new mean = 28.57 years.
Mathematics
Average / Arithmetic Mean
A squad of 13 people has average age 29. A member aged 42 is replaced by one aged 22. Find the new average age.
A. 26.46 years
B. 28.46 years
C. 29.46 years
D. 27.46 years
Correct Answer: D
Total changes by -20; new mean = 27.46 years.
Mathematics
Average / Arithmetic Mean
A squad of 12 people has average age 28. A member aged 41 is replaced by one aged 21. Find the new average age.
A. 27.33 years
B. 28.33 years
C. 26.33 years
D. 25.33 years
Correct Answer: C
Total changes by -20; new mean = 26.33 years.
Mathematics
Average / Arithmetic Mean
A squad of 11 people has average age 27. A member aged 40 is replaced by one aged 20. Find the new average age.
A. 26.18 years
B. 27.18 years
C. 25.18 years
D. 24.18 years
Correct Answer: C
Total changes by -20; new mean = 25.18 years.
Mathematics
Average / Arithmetic Mean
A family of 6 people has average age 37. After 3 years, a relative aged 27 at that future time joins them. What is the new average then?
A. 40.14 years
B. 37.14 years
C. 38.14 years
D. 39.14 years
Correct Answer: C
Future total of original members = 6×(37+3); add 27 and divide by 7.
Mathematics
Average / Arithmetic Mean
A family of 5 people has average age 36. After 2 years, a relative aged 26 at that future time joins them. What is the new average then?
A. 38 years
B. 37 years
C. 36 years
D. 35 years
Correct Answer: C
Future total of original members = 5×(36+2); add 26 and divide by 6.