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15 Averages Questions and Answers

15 solved Averages questions with step-by-step explanations. Includes formulas, shortcuts, and tips for placement tests and competitive exams.

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Averages are a simple yet powerful concept in aptitude tests. The average (or arithmetic mean) of a set of numbers is their sum divided by the count. The formula Average = Sum ÷ Count and its reverse Sum = Average × Count are the two tools you need for most problems. Common question types include: finding a missing value when the average and other values are known, calculating new averages when values are added or removed, and weighted averages. Averages frequently appear combined with other topics like age problems, cricket scores, and temperature readings. Below are solved average questions with clear explanations.

Q1 Easy

Class A has 50 students with average marks 44. Class B has 50 students with average 52. Find combined average.

  • A. 45
  • B. 48 ✓
  • C. 50
  • D. 46
Explanation: Combined average = (50x44+50x52)/(100) = 48.
Q2 Easy

Average of 6 numbers is 44. After adding 30, what is the new average?

  • A. 39
  • B. 42 ✓
  • C. 44
  • D. 40
Explanation: New average = (6x44+30)/7 = 42.
Q3 Easy

Class A has 29 students with average marks 61. Class B has 29 students with average 43. Find combined average.

  • A. 52 ✓
  • B. 49
  • C. 54
  • D. 50
Explanation: Combined average = (29x61+29x43)/(58) = 52.
Q4 Easy

Average of 5 numbers is 60. After adding 24, what is the new average?

  • A. 52
  • B. 54 ✓
  • C. 56
  • D. 51
Explanation: New average = (5x60+24)/6 = 54.
Q5 Easy

Average of 5 numbers is 54. 4 numbers are 90, 64, 35, 81. Find the missing number.

  • A. 10
  • B. 6
  • C. 4
  • D. 0 ✓
Explanation: Total sum = 5x54 = 270. Missing = Total - Known sum = 0.
Q6 Easy

Average of 5 numbers is 66. After adding 30, what is the new average?

  • A. 58
  • B. 62
  • C. 60 ✓
  • D. 57
Explanation: New average = (5x66+30)/6 = 60.
Q7 Medium

Class A has 43 students with average marks 67. Class B has 43 students with average 61. Find combined average.

  • A. 62
  • B. 61
  • C. 66
  • D. 64 ✓
Explanation: Combined average = (43x67+43x61)/(86) = 64.
Q8 Medium

Average of 6 numbers is 49. 5 numbers are 33, 33, 32, 93, 94. Find the missing number.

  • A. 13
  • B. 5
  • C. 9 ✓
  • D. 3
Explanation: Total sum = 6x49 = 294. Missing = Total - Known sum = 9.
Q9 Medium

Class A has 26 students with average marks 74. Class B has 26 students with average 58. Find combined average.

  • A. 64
  • B. 68
  • C. 66 ✓
  • D. 63
Explanation: Combined average = (26x74+26x58)/(52) = 66.
Q10 Medium

Average of 6 numbers is 53. 5 numbers are 47, 84, 23, 54, 51. Find the missing number.

  • A. 53
  • B. 63
  • C. 59 ✓
  • D. 55
Explanation: Total sum = 6x53 = 318. Missing = Total - Known sum = 59.
Q11 Medium

Class A has 42 students with average marks 75. Class B has 42 students with average 47. Find combined average.

  • A. 63
  • B. 58
  • C. 59
  • D. 61 ✓
Explanation: Combined average = (42x75+42x47)/(84) = 61.
Q12 Hard

Average of 7 numbers is 47. 6 numbers are 88, 75, 45, 29, 23, 50. Find the missing number.

  • A. 15
  • B. 13
  • C. 19 ✓
  • D. 23
Explanation: Total sum = 7x47 = 329. Missing = Total - Known sum = 19.
Q13 Hard

Average of 6 numbers is 46. 5 numbers are 45, 69, 82, 42, 90. Find the missing number.

  • A. -54
  • B. -48
  • C. -52 ✓
  • D. -39
Explanation: Total sum = 6x46 = 276. Missing = Total - Known sum = -52.
Q14 Hard

Average of 7 numbers is 52. 6 numbers are 88, 61, 26, 85, 37, 35. Find the missing number.

  • A. 32 ✓
  • B. 28
  • C. 36
  • D. 26
Explanation: Total sum = 7x52 = 364. Missing = Total - Known sum = 32.
Q15 Hard

Class A has 32 students with average marks 45. Class B has 32 students with average 61. Find combined average.

  • A. 51
  • B. 50
  • C. 53 ✓
  • D. 55
Explanation: Combined average = (32x45+32x61)/(64) = 53.

Key Takeaways

  • Sum = Average × Count — this is the most useful formula for average problems.
  • When values are added/removed: update the sum first, then recalculate average.
  • Weighted average = (w1×v1 + w2×v2) / (w1 + w2) for different weights.

Frequently Asked Questions

What is the formula for average?

Average = Sum of all values ÷ Number of values. The reverse is equally useful: Sum = Average × Number of values.

How do I find a missing value when average is known?

Missing value = (Average × Total count) - Sum of known values. This single formula solves most average-based problems.

More Averages Practice Resources

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