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Free Averages MCQs with Answers

90 Averages MCQs from Mathematics, each with the correct answer and a written explanation of why it is correct. Free and unlimited, with no account needed.

An average represents the total of a set of values divided by the number of values, and a weighted average gives different importance to different groups. Problems involve missing values, combined averages, replacement of observations, and changes in the average, so the total and count must be tracked separately.

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21. The average monthly salary of 20 employees in an organisation is Rs. 1500. If the manager's salary is added, then the average salary increases by Rs. 100. What is the manager's monthly salary?

  • A. Rs. 2000
  • B. Rs. 2400
  • C. Rs. 3600
  • D. Rs. 4800

Explanation: The original total salary is 20 x Rs. 1500 = Rs. 30,000. With the manager included, the total becomes 21 x Rs. 1600 = Rs.

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Correct answer: Rs. 3600

22. The average monthly income of P and Q is Rs. 5050. The average monthly income of Q and R is 6250 and the average monthly income of P and R is Rs. 5200. The monthly income of P is____________?

  • A. Rs. 3500
  • B. Rs. 4000
  • C. Rs. 4050
  • D. Rs. 5000Downloading Interactive Party Trivia Games

Explanation: The pair totals are P + Q = 2 x Rs. 5050 = Rs. 10,100, Q + R = Rs. 12,500, and P + R = 2 x Rs. 5200 = Rs. 10,400.

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Correct answer: Rs. 4000

23. The average age of 15 students of a class is 15 years. Out of these, the average age of 5 students is 14 years and that of the other 9 students is 16 years. The age of the 15th student is____________?

  • A. 11 years
  • B. 14 years
  • C. 15 years
  • D. 15 2/7 years

Explanation: The total age of all 15 students is 15 x 15 = 225 years. The 5 students contribute 5 x 14 = 70 years and the other 9 contribute 9 x 16 =…

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Correct answer: 11 years

24. A pupil's marks were wrongly entered as 83 instead of 63. Due to the average marks for the class got increased by half. The number of pupils in the class is___________?

  • A. 10
  • B. 20
  • C. 40
  • D. 73

Explanation: The incorrect entry increased the student's marks by 83 - 63 = 20 marks.

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Correct answer: 40

25. The mean of 50 observations was 36. It was found later that an observation 48 was wrongly taken as 23. The corrected new mean is___________?

  • A. 35.2
  • B. 36.1
  • C. 36.5
  • D. 39.1

Explanation: The original total was 50 x 36 = 1800. Correcting an observation from 23 to 48 increases the total by 48 - 23 = 25, giving 1825, and the…

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Correct answer: 36.5

26. If the arithmetic mean of seventy five numbers is calculated, it is 35. If each number is increased by 5, then mean of new number is___________?

  • A. 30
  • B. 40
  • C. 70
  • D. 90

Explanation: Adding 5 to every observation increases the arithmetic mean by exactly 5, because the same constant is added to every value.

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Correct answer: 40

27. In the first 10 overs of a cricket game, the run rate was only 3.2. What should be the rate in the remaining 40 overs to reach the target of 282 runs?

  • A. 6.25
  • B. 6.5
  • C. 6.75
  • D. 7

Explanation: The first 10 overs produced 10 x 3.2 = 32 runs. The remaining runs required are 282 - 32 = 250 runs, and over the remaining 40 overs the…

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Correct answer: 6.25

28. The average of runs of a cricket player of 10 innings was 32. How many runs must he make in his next innings so as to increase his average of runs by 4?

  • A. 2
  • B. 4
  • C. 70
  • D. 76

Explanation: His first 10 innings totalled 10 x 32 = 320 runs. To average 36 runs after 11 innings, his total must be 11 x 36 = 396 runs, so the next…

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Correct answer: 76

29. The average of 35 students in a class is 16 years. The average age of 21 students is 14. What is the average age of remaining 14 students?

  • A. 15 years
  • B. 17 years
  • C. 18 years
  • D. 19 years

Explanation: The total age of 35 students is 35 x 16 = 560 years, while the 21 students contribute 21 x 14 = 294 years.

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Correct answer: 19 years

30. The average of five numbers is 27. If one number is excluded, the average becomes 25. The excluded number is__________?

  • A. 25
  • B. 27
  • C. 30
  • D. 35

Explanation: The total of five numbers is 5 x 27 = 135. After excluding one number, the remaining total is 4 x 25 = 100, so the excluded number is 135…

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Correct answer: 35

31. A library has an average of 510 visitors on Sunday and 240 on other days. The average number of visitors per day in a month of 30 days beginning with a Sunday is___________?

  • A. 250
  • B. 276
  • C. 280
  • D. 285Quiz Mode Feature

Explanation: In a 30-day month beginning on Sunday, there are five Sundays, so the total visitors are 5 x 510 + 25 x 240 = 2550 + 6000 = 8550 visitors.

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Correct answer: 285Quiz Mode Feature

32. A family consists of grandparents, parents and three grandchildren. The average age of the grandparents is 67 years, that of the parents is 35 years and that of the grandchildren is 6 years. What is the average age of the family?

  • A. 28 4/7 years
  • B. 31 5/7 years
  • C. 32 1/7 years
  • D. None of these

Explanation: There are 2 grandparents, 2 parents and 3 grandchildren, making 7 family members.

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Correct answer: 31 5/7 years

33. The average of five consecutive odd numbers is 61. What is the difference between the highest and lowest numbers?

  • A. 2
  • B. 5
  • C. 8
  • D. Cannot be determined

Explanation: For consecutive odd numbers, the average is the middle number, so the five numbers are 57, 59, 61, 63 and 65.

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Correct answer: 8

34. The average of non-zero number and its square is 5 times the number. The number is__________?

  • A. 9
  • B. 17
  • C. 29
  • D. 295

Explanation: Let the non-zero number be n. Its average with its square is (n + n²) / 2, and this equals 5n.

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Correct answer: 9

35. The average of the two-digit numbers, which remain the same when the digits interchange their positions, is__________?

  • A. 33
  • B. 44
  • C. 55
  • D. 66

Explanation: Two-digit numbers unchanged by reversing their digits are 11, 22, 33, 44, 55, 66, 77, 88 and 99.

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Correct answer: 55

36. The average of first five multiples of 3 is____________?

  • A. 3
  • B. 9
  • C. 12
  • D. 15

Explanation: The first five multiples of 3 are 3, 6, 9, 12 and 15. Their sum is 45, and their average is 45 / 5 = 9.

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Correct answer: 9

37. Find the average of all the numbers between 6 and 34 which are divisible by 5.

  • A. 18
  • B. 20
  • C. 24
  • D. 30

Explanation: The numbers divisible by 5 between 6 and 34 are 10, 15, 20, 25 and 30. Their average is (10 + 15 + 20 + 25 + 30) / 5 = 100 / 5 = 20.

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Correct answer: 20

38. The average of 20 numbers is zero. Of them, at the most, how many may be greater than zero?

  • A. 0
  • B. 1
  • C. 10
  • D. 19

Explanation: If 19 numbers are greater than 0, the twentieth number can be negative enough to make the total 0, so 19 is possible.

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Correct answer: 19

39. Sarfaraz obtained 76, 65, 82, 67 and 85 marks (out of 100) in English, Mathematics, Physics, Chemistry and Biology. What are his average marks?

  • A. 65
  • B. 69
  • C. 72
  • D. None of these

Explanation: The total marks are 76 + 65 + 82 + 67 + 85 = 375 marks. The average is 375 marks / 5 subjects = 75 marks, which is not listed in options…

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Correct answer: None of these

40. The average weight of a group of persons increased from 48 kg to 51 kg, when two persons weighing 78 kg and 93 kg join the group. Find the initial number of members in the group?

  • A. 21
  • B. 22
  • C. 23
  • D. 24

Explanation: If the initial group had n persons, its total weight was 48n kilograms.

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Correct answer: 23
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