Average Practice Questions

5 questions per page • Detailed step-by-step solutions

Question 1
Easy
What is the average of the first 44 natural numbers?
A 22.5
B 22
C 23
D 45
Correct Answer: A

Explanation:

Step 1: Sum of the first n natural numbers = n(n + 1)/2 = 44 × 45/2 = 990. Step 2: Number of terms = 44. Step 3: Average = 990 ÷ 44 = 22.5.
Question 2
Medium
The present average age of A, B and C is 44 years. 6 years ago, the average age of A and C was 48 years. What is the present age of B?
A 36 years
B 30 years
C 24 years
D 25 years
Correct Answer: C

Explanation:

Step 1: Present A + B + C = 3 × 44 = 132. Step 2: 6 years ago A + C = 2 × 48 = 96; each has aged 6 years since, so present A + C = 96 + 2 × 6 = 108. Step 3: B = 132 − 108 = 24 years.
Question 3
Medium
The average of a non-zero number and its square is 23 times the number. What is the number?
A 46
B 45
C 47
D 23
Correct Answer: B

Explanation:

Step 1: (x + x²)/2 = 23x → x + x² = 46x. Step 2: Divide by x (x ≠ 0): 1 + x = 46. Step 3: x = 46 − 1 = 45. Check: (45 + 2025)/2 = 1035 = 23 × 45 ✓.
Question 4
Medium
The average marks of a class is 69. The average marks of the boys is 88 and that of the girls is 68. What is the ratio of the number of boys to the number of girls?
A 19 : 1
B 2 : 19
C 1 : 19
D 1 : 20
Correct Answer: C

Explanation:

Step 1: Let there be x boys and y girls. Total marks: 88x + 68y = 69(x + y). Step 2: Rearranging: (88 − 69)x = (69 − 68)y → 19x = y. Step 3: x : y = 1 : 19 = 1 : 19.
Question 5
Easy
The average of x, x + 6, x + 12, x + 18 and x + 24 is 60. What is the value of x?
A 54
B 36
C 72
D 48
Correct Answer: D

Explanation:

Step 1: Sum = 5x + (6 + 12 + 18 + 24) = 5x + 60. Step 2: Average = (5x + 60)/5 = x + 12 = 60. Step 3: x = 60 − 12 = 48.