Q. The average age of a group of 5 people is 30 years. If a new person joins the group, making the average age 32 years, what is the age of the new person?
A.35
B.40
C.45
D.50
Solution
Total age of 5 people = 5 * 30 = 150. New total age = 6 * 32 = 192. Age of new person = 192 - 150 = 42.
Correct Answer: B — 40
Q. The average of 10 numbers is 50. If one number is increased by 10, what will be the new average?
A.50
B.51
C.52
D.53
Solution
The total of the 10 numbers is 10 * 50 = 500. If one number is increased by 10, the new total becomes 500 + 10 = 510. The new average is 510 / 10 = 51.
Correct Answer: B — 51
Q. The average of 4 consecutive integers is 25. What is the largest of these integers?
A.26
B.27
C.28
D.29
Solution
Let the integers be x, x+1, x+2, x+3. Average = (4x + 6) / 4 = 25. Solving gives x = 24. Largest integer = x + 3 = 27.
Correct Answer: C — 28
Q. The average of 4 consecutive integers is 25. What is the smallest of these integers?
A.23
B.24
C.25
D.26
Solution
Let the integers be x, x+1, x+2, x+3. Average = (4x + 6) / 4 = 25. So, 4x + 6 = 100. Therefore, x = 23.
Correct Answer: A — 23
Q. The average of 4 numbers is 30. If one number is 10, what is the average of the other three numbers?
A.28
B.30
C.32
D.34
Solution
Total of 4 numbers = 4 * 30 = 120. Total of other three numbers = 120 - 10 = 110. Average of other three = 110 / 3 = 36.67, approximately 36.
Correct Answer: A — 28
Q. The average of 4 numbers is 30. If one number is increased by 10, what will be the new average?
A.30
B.32.5
C.35
D.37.5
Solution
Total = 30 * 4 = 120. New total = 120 + 10 = 130. New average = 130 / 4 = 32.5.
Correct Answer: B — 32.5
Q. The average of 5 numbers is 12. If one number is removed, the average becomes 10. What is the removed number?
A.8
B.10
C.12
D.14
Solution
Total of 5 numbers = 5 * 12 = 60. Total of 4 numbers = 4 * 10 = 40. Removed number = 60 - 40 = 20.
Correct Answer: D — 14
Q. The average of 5 numbers is 40. If the largest number is 60, what is the average of the other four numbers?
A.35
B.40
C.45
D.50
Solution
The total of the 5 numbers is 5 * 40 = 200. The sum of the other four numbers is 200 - 60 = 140. The average of the other four numbers is 140 / 4 = 35.
Correct Answer: A — 35
Q. The average of 8 numbers is 12. If one number is removed, the average becomes 10. What is the removed number?
A.16
B.18
C.20
D.22
Solution
The total of the 8 numbers is 8 * 12 = 96. The total of the remaining 7 numbers is 7 * 10 = 70. Therefore, the removed number is 96 - 70 = 26.
Correct Answer: C — 20
Q. The average of 8 numbers is 50. If one number is increased by 10, what will be the new average?
A.50
B.51
C.52
D.53
Solution
Total of 8 numbers = 8 * 50 = 400. New total = 400 + 10 = 410. New average = 410 / 8 = 51.25, approximately 51.
Correct Answer: B — 51
Q. The average of five numbers is 20. If one number is excluded, the average becomes 18. What is the excluded number?
A.22
B.20
C.18
D.16
Solution
Total of five numbers = 5 * 20 = 100. Total of four numbers = 4 * 18 = 72. Excluded number = 100 - 72 = 28.
Correct Answer: A — 22
Q. The average of three consecutive integers is 20. What is the largest of these integers?
A.19
B.20
C.21
D.22
Solution
Let the integers be x, x+1, x+2. Average = (x + (x+1) + (x+2)) / 3 = 20. Solving gives x = 19, largest integer = 21.
Correct Answer: C — 21
Q. The average of three numbers is 15. If one of the numbers is 12, what is the average of the other two numbers?
A.14
B.15
C.16
D.17
Solution
Total of three numbers = 3 * 15 = 45. Sum of other two numbers = 45 - 12 = 33. Average = 33 / 2 = 16.5.
Correct Answer: B — 15
Q. The average of three numbers is 20. If one number is 10, what is the average of the other two numbers?
A.15
B.20
C.25
D.30
Solution
Total of three numbers = 20 * 3 = 60. The sum of the other two = 60 - 10 = 50. Average = 50 / 2 = 25.
Correct Answer: A — 15
Q. The average of three numbers is 30. If one of the numbers is 10, what is the average of the other two numbers?
A.25
B.30
C.35
D.40
Solution
Let the three numbers be a, b, and c. We have (a + b + c) / 3 = 30. Thus, a + b + c = 90. If c = 10, then a + b = 90 - 10 = 80. The average of a and b is 80 / 2 = 40.
Correct Answer: A — 25
Q. The average of two numbers is 40. If one number is 30, what is the other number?
A.50
B.60
C.70
D.80
Solution
Let the other number be x. (30 + x) / 2 = 40. So, 30 + x = 80. Therefore, x = 50.
Correct Answer: A — 50
Q. What is the average of the first five prime numbers?
A.5
B.6
C.7
D.8
Solution
The first five prime numbers are 2, 3, 5, 7, 11. Average = (2 + 3 + 5 + 7 + 11) / 5 = 28 / 5 = 5.6.
Correct Answer: C — 7
Q. What is the average of the numbers 10, 20, and 30?
