1.The average of four numbers is 20. If one of the numbers is 25, what is the sum of the other three numbers?

a) 55

b) 60

c) 65

d) 70

2.If the average of five consecutive odd numbers is 15, what is the largest of these numbers?

a) 13

b) 15

c) 17

d) 19

3.The average of a, b, and c is 25. If a = 20 and b = 30, what is the value of c?

a) 25

b) 20

c) 30

d) 35

4.The average of 5, 10, 15, 20, and x is 18. What is the value of x?

a) 35

b) 30

c) 25

d) 20

5.The average of the first 10 natural numbers is:

a) 5.5

b) 5

c) 6

d) 6.5

6.The average age of a group of 10 students is 15 years. If the age of the teacher is added, the average age increases by 1 year. What is the age of the teacher?

a) 25 years

b) 26 years

c) 27 years

d) 28 years

7.If the average of four numbers is 24 and the average of three of these numbers is 20, what is the fourth number?

a) 24

b) 28

c) 32

d) 36

8.The average of 10 numbers is 40. If each number is increased by 5, what is the new average?

a) 45

b) 50

c) 55

d) 60

9.The average of six numbers is 50. If one of the numbers is removed, the average of the remaining numbers is 45. What is the number that was removed?

a) 60

b) 70

c) 80

d) 90

10.The average of the first n natural numbers is 8. What is the value of n?

a) 15

b) 16

c) 17

d) 18

11.The average of 20 numbers is 0. Of them, at most, how many may be greater than 0?

a) 0

b) 1

c) 10

d) 19

12.If the average of x, y, and z is 30 and x + y + z = 90, what is the average of x/3, y/3, and z/3?

a) 10

b) 15

c) 20

d) 30

13.The average of five different numbers is 12. If the largest number is 18, what is the average of the other four numbers?

a) 10

b) 11

c) 12

d) 13

14.The average of three consecutive multiples of 3 is 27. What is the smallest of these numbers?

a) 21

b) 24

c) 27

d) 30

15.If the average of six numbers is 35 and the average of four of these numbers is 30, what is the average of the other two numbers?

a) 40

b) 45

c) 50

d) 55

16.The average of three numbers is 45. If one of the numbers is 30, what is the average of the other two numbers?

a) 40

b) 45

c) 50

d) 55

17.The average weight of a class of 30 students is 60 kg. If the weight of the teacher is included, the average weight increases by 0.5 kg. What is the weight of the teacher?

a) 65 kg

b) 70 kg

c) 75 kg

d) 80 kg

18.The average of the first 20 even numbers is:

a) 20

b) 21

c) 22

d) 23

19.If the average of a, b, c, and d is 50, and a + b + c = 120, what is the value of d?

a) 30

b) 40

c) 50

d) 60

20.The average of five numbers is 60. If one of the numbers is removed, the average of the remaining numbers is 58. What is the number that was removed?

a) 60

b) 65

c) 70

d) 75

21.The average of four consecutive numbers is 23.5. What is the smallest of these numbers?

a) 21

b) 22

c) 23

d) 24

22.If the average of three numbers x, y, and z is 20, and x = y = 10, what is the value of z?

a) 30

b) 40

c) 50

d) 60

23.The average of the first 15 multiples of 3 is:

a) 20

b) 21

c) 22

d) 23

24.If the average of n numbers is A and the average of m other numbers is B, what is the average of all the numbers?

a) A + B/2

b) nA + mB/n + m

c) nB + mA/n + m

d) A – B/n + m

25.The average age of a group of 5 men is 30 years. If one man leaves the group, the average age of the remaining men becomes 28 years. What is the age of the man who left?

a) 35 years

b) 40 years

c) 45 years

d) 50 years

26.The average of five numbers is 25. If one of the numbers is replaced by 35, the average becomes 27. What is the number that was replaced?

a) 15

b) 20

c) 25

d) 30

27.If the average of x, y, z, and w is 50 and the average of x and y is 40, what is the average of z and w?

a) 50

b) 55

c) 60

d) 65

28.The average of 100 observations is 50. If one observation is wrongly taken as 60 instead of 50, what will be the correct average?

a) 49.9

b) 50.1

c) 50

d) 49.8

29.The average of 11 numbers is 10.9. If the average of the first 6 numbers is 10.5 and the average of the last 6 numbers is 11.4, what is the 6th number?

a) 10

b) 11

c) 12

d) 13

30.If the average of five numbers is 60 and the average of another five numbers is 70, what is the average of all ten numbers?

a) 64

b) 65

c) 66

d) 67