Quantitative Aptitude

Average questions with solutions

Average questions are short and appear in every SSC and railway paper. Most can be solved with totals instead of formulas.

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Prepared by the CBTAdda content team · Updated 28 October 2026 · How we check our content

How to solve average questions

Total = average × number of items. Work with totals, then divide at the end.
For consecutive numbers, the average is the middle number.
When a new person joins and the average changes by d, their value = new average + (old count × d), or simply new total − old total.

Common trap: When someone joins, the count increases by one. Using the old count for the new total is the classic slip.

12 practice questions

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The average age of 24 students is 25 years. When the teacher's age is included, the average rises by 1 year. What is the teacher's age?
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Answer: (A) 50 years. New total = 25 × 26 = 650. Old total = 24 × 25 = 600. Teacher = 50 years.
The average of 7 consecutive even numbers is 26. What is the largest of them?
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Answer: (A) 32. The middle number equals the average, 26. There are 3 numbers above it, each 2 apart, so the largest is 26 + 6 = 32.
The average of 7 consecutive odd numbers is 47. What is the largest of them?
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Answer: (A) 53. The middle number equals the average, 47. There are 3 numbers above it, each 2 apart, so the largest is 47 + 6 = 53.
The average of 5 consecutive numbers is 38. What is the largest of them?
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Answer: (C) 40. The middle number equals the average, 38. There are 2 numbers above it, each 1 apart, so the largest is 38 + 2 = 40.
The average age of 14 students is 40 years. When the teacher's age is included, the average rises by 1 year. What is the teacher's age?
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Answer: (A) 55 years. New total = 15 × 41 = 615. Old total = 14 × 40 = 560. Teacher = 55 years.
The average of 9 consecutive numbers is 41. What is the largest of them?
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Answer: (D) 45. The middle number equals the average, 41. There are 4 numbers above it, each 1 apart, so the largest is 41 + 4 = 45.
The average of 5 consecutive even numbers is 58. What is the largest of them?
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Answer: (B) 62. The middle number equals the average, 58. There are 2 numbers above it, each 2 apart, so the largest is 58 + 4 = 62.
The average age of 22 students is 28 years. When the teacher's age is included, the average rises by 2 years. What is the teacher's age?
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Answer: (D) 74 years. New total = 23 × 30 = 690. Old total = 22 × 28 = 616. Teacher = 74 years.
The average age of 14 students is 21 years. When the teacher's age is included, the average rises by 2 years. What is the teacher's age?
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Answer: (A) 51 years. New total = 15 × 23 = 345. Old total = 14 × 21 = 294. Teacher = 51 years.
The average of 9 consecutive numbers is 53. What is the largest of them?
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Answer: (C) 57. The middle number equals the average, 53. There are 4 numbers above it, each 1 apart, so the largest is 53 + 4 = 57.
The average age of 22 students is 33 years. When the teacher's age is included, the average rises by 1 year. What is the teacher's age?
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Answer: (B) 56 years. New total = 23 × 34 = 782. Old total = 22 × 33 = 726. Teacher = 56 years.
What is the average of the first 30 natural numbers?
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Answer: (C) 15.5. Average of 1 to n = (n + 1) ÷ 2 = 31 ÷ 2 = 15.5.