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SikkimPSC Averages — practice questions — page 2

Explore 37 free Averages questions in SikkimPSC Quantitative Aptitude. Open each question or exercise to read its content, reference answers and available explanation.

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Averages questions and exercises with answers

Showing questions 31–37 of 37.

The average of the first 10 natural numbers is:Read the answer and worked solution →The average of 10 numbers is 45. A new number, 100, is added to the set. The new average is:Read the answer and worked solution →The class mark of the class interval 10-25 is:Read the answer and worked solution →The average of 6 numbers is 8. If the number 12 is removed, the average of the remaining 5 is:Read the answer and worked solution →In a branch, 30 clerks average 60 marks and 20 officers average 70. The average of all 50 staff is:Read the answer and worked solution →The average of 15 numbers is 12. The first 8 average 11 and the last 8 average 14. The 8th number is:Read the answer and worked solution →A batsman's average over 16 innings is 36. To raise the average to 38 in the 17th innings, he must score:Read the answer and worked solution →

Worked practice questions

The average of the first 10 natural numbers is:

  1. 5.5
  2. 5
  3. 6
  4. 6.5
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Correct answer: A. 5.5

1. The first 10 natural numbers are 1 through 10. 2. Their sum is 10 x 11 / 2 = 55. 3. The average is the sum divided by the count, so 55 / 10. 4. That gives 5.5. 5. Answering 5 would be taking the middle of 1 to 10 carelessly; with an even count the mean falls between 5 and 6. _Source: syllabus Maths, Ch 13 'Statistics', S13.2 Mean of Grouped Data_

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The average of 10 numbers is 45. A new number, 100, is added to the set. The new average is:

  1. 45
  2. 50
  3. 55
  4. 72.5
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Correct answer: B. 50

1. Recover the total first: average x count = 45 x 10 = 450. 2. Adding the new number makes the total 450 + 100 = 550. 3. The count is now 11. 4. So the new average is 550 / 11 = 50. 5. 72.5 comes from averaging 45 and 100 directly, which ignores that one number cannot outweigh ten. _Source: syllabus Maths, Ch 13 'Statistics', S13.2 Mean of Grouped Data_

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The class mark of the class interval 10-25 is:

  1. 12.5
  2. 15
  3. 17.5
  4. 20
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Correct answer: C. 17.5

1. A class interval is treated as if it were centred on its mid-point. 2. The mid-point of a class, also called its class mark, is the average of its upper and lower limits. 3. Here that is (10 + 25) / 2. 4. So the class mark is 17.5. 5. 15 is the width of the class, not its centre, which is the usual slip. _Source: syllabus Maths, Ch 13 'Statistics', S13.2 Mean of Grouped Data_

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