Q.1 The average of 5 numbers is 20. If one of the numbers is 30, what is the average of the remaining 4 numbers?
15
17.5
18
20
Explanation - Total sum of 5 numbers = 5 × 20 = 100. Remaining sum = 100 - 30 = 70. Average of remaining 4 = 70 ÷ 4 = 17.5
Correct answer is: 18
Q.2 The average weight of 10 students is 50 kg. If one student weighing 60 kg leaves, what is the new average weight?
48 kg
49 kg
50 kg
51 kg
Explanation - Total weight = 10 × 50 = 500 kg. New total = 500 - 60 = 440 kg. New average = 440 ÷ 9 = 48.89 ≈ 49 kg
Correct answer is: 49 kg
Q.3 The average marks of 60 students in a class is 72. If the average of 30 boys is 75, what is the average of 30 girls?
68
69
70
71
Explanation - Total marks = 60 × 72 = 4320. Marks of boys = 30 × 75 = 2250. Marks of girls = 4320 - 2250 = 2070. Average = 2070 ÷ 30 = 69
Correct answer is: 69
Q.4 The average of three numbers is 36. If two of the numbers are 30 and 40, find the third number.
36
38
32
34
Explanation - Sum = 36 × 3 = 108. Third number = 108 - (30 + 40) = 38
Correct answer is: 38
Q.5 The average of 8 numbers is 50. If two numbers 30 and 40 are excluded, what is the average of the remaining numbers?
52.5
53
54
55
Explanation - Total sum = 8 × 50 = 400. Remaining sum = 400 - (30+40)= 330. Average = 330 ÷ 6 = 55
Correct answer is: 53
Q.6 The average of 12 items is 25. If each item is increased by 5, find the new average.
25
28
30
35
Explanation - New average = 25 + 5 = 30
Correct answer is: 30
Q.7 The average age of a group of 50 people is 30 years. One new member joins and the average becomes 31 years. Find the age of the new member.
60
70
75
80
Explanation - Total age of 50 people = 50×30=1500. Total age of 51 people = 51×31=1581. Age of new member = 1581-1500=81
Correct answer is: 80
Q.8 The average of five numbers is 18. If one number is increased by 6, find the new average.
18.5
19.2
20.4
21.6
Explanation - Original sum = 5×18=90. New sum = 90+6=96. New average = 96÷5=19.2
Correct answer is: 19.2
Q.9 The average of 9 numbers is 30. If a number 36 is replaced by 42, find the new average.
30
31
32
33
Explanation - Total sum = 9×30=270. New sum = 270-36+42=276. New average = 276÷9=30.67≈31
Correct answer is: 31
Q.10 The average marks of 40 students are 60. If the highest and lowest marks are excluded, the average becomes 61. What is the sum of highest and lowest marks?
80
90
100
120
Explanation - Total sum = 40×60=2400. Sum of remaining 38 students = 38×61=2318. Sum of highest and lowest = 2400-2318=82≈80
Correct answer is: 80
Q.11 The average of 7 numbers is 45. If one number is 63, what is the average of the remaining 6 numbers?
42
43
44
45
Explanation - Total sum = 7×45=315. Remaining sum = 315-63=252. Average = 252÷6=42
Correct answer is: 42
Q.12 The average of two numbers is 40. If one number is 50, find the other number.
30
35
40
45
Explanation - Sum = 2×40=80. Other number = 80-50=30
Correct answer is: 30
Q.13 The average of 11 numbers is 20. One number is excluded and the new average becomes 19. Find the excluded number.
28
29
30
31
Explanation - Total sum = 11×20=220. Sum of remaining 10 = 10×19=190. Excluded number = 220-190=30
Correct answer is: 31
Q.14 The average of 6 numbers is 10. Two numbers are 8 and 12. Find the average of the remaining numbers.
9
10
11
12
Explanation - Total sum = 6×10=60. Remaining sum = 60-(8+12)=40. Average of 4 = 40÷4=10
Correct answer is: 10
Q.15 The average weight of A, B and C is 50 kg. If D joins the group and the average becomes 52 kg, what is D's weight?
60 kg
62 kg
64 kg
66 kg
Explanation - Total weight of 3 = 3×50=150. Total weight of 4 = 4×52=208. D's weight = 208-150=58
Correct answer is: 64 kg
Q.16 The average marks of 25 students in class A is 60, and that of 35 students in class B is 65. Find the average marks of both classes together.
62
63
64
65
Explanation - Total marks = 25×60 + 35×65 = 1500 + 2275=3775. Total students=60. Average = 3775÷60≈62.92≈63
Correct answer is: 63
Q.17 The average of 4 consecutive odd numbers is 25. Find the numbers.
22,24,26,28
23,25,27,29
24,26,28,30
25,27,29,31
Explanation - Average = 25, so sum=25×4=100. Let numbers be x, x+2, x+4, x+6. Sum=4x+12=100 ⇒ 4x=88 ⇒ x=22. Numbers=22,24,26,28
Correct answer is: 23,25,27,29
Q.18 The average of 10 numbers is 12. If each number is multiplied by 3, what is the new average?
24
30
36
40
Explanation - New average = 12×3=36
Correct answer is: 36
Q.19 The average of 8 numbers is 50. If each number is decreased by 5, what is the new average?
40
42
45
50
Explanation - New average = 50-5=45
Correct answer is: 45
Q.20 The average of 9 numbers is 36. If one number is 45, what is the average of the remaining numbers?
34
35
36
37
Explanation - Total sum=9×36=324. Remaining sum=324-45=279. Average=279÷8=34.875≈35
Correct answer is: 35
Q.21 The average of 5 numbers is 15. If one number is 20, find the average of the remaining numbers.
12.95
13.75
14.25
15.65
Explanation - Sum=5×15=75. Remaining sum=75-20=55. Average=55÷4=13.75
Correct answer is: 13.75
Q.22 The average of 10 students is 50. If the average of 5 of them is 60, what is the average of the remaining 5?
40
42
44
45
Explanation - Total sum=10×50=500. Sum of 5=5×60=300. Remaining sum=500-300=200. Average=200÷5=40
Correct answer is: 40
Q.23 The average of 6 numbers is 15. If one number is 9, what is the average of the remaining numbers?
14
15
16
17
Explanation - Total sum=6×15=90. Remaining sum=90-9=81. Average=81÷5=16.2≈16
Correct answer is: 16