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All Free Mathematics MCQs with Answers

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1,551 questions · page 12 of 78

221. The average of 18 observations was calculated and it was 124. Later on it was discovered that two observations 46 and 82 were incorrect. The correct values are 64 and 28. The correct average of 18 observations is___________?

  • A. 123
  • B. 137
  • C. 121
  • D. 122

Explanation: The originally recorded total is 18 x 124 = 2232. Replacing 46 and 82 by 64 and 28 changes the total by (64 + 28) - (46 + 82) = -36, so…

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Correct answer: 122

222. The mean marks of 30 students in a class is 58.5. Later on it was found that 75 was wrongly recorded as 57. Find the correct them.

  • A. 57.4
  • B. 57.5
  • C. 58.9
  • D. 59.1Everyday Science Quiz

Explanation: The recorded total is 30 students x 58.5 marks = 1755 marks. Correcting 57 marks to 75 marks adds 18 marks, so the new average is (1755 +…

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Correct answer: 59.1Everyday Science Quiz

223. The average of women and child workers in a factory was 15%yr. The average age of all the 16 children was 8yr and average age of women workers was 22 yrs if ten women workers were married then the number of unmarried women workers were________?

  • A. 16
  • B. 12
  • C. 8
  • D. 6

Explanation: Interpreting the damaged text as a combined average age of 15 years, let the number of women be w.

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Correct answer: 6

224. The average age of students of a class is 15.8 years. The average age of boys in the class is 16.4 years and that of the girls is 15.4 years. The ration of the number of boys to the number of girls in the class is___________?

  • A. 1:2
  • B. 2:3
  • C. 3:4
  • D. 3:5

Explanation: The overall average of 15.8 years is 0.4 years above the girls' average of 15.4 years, while the difference between boys and girls is 1…

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Correct answer: 2:3

225. In an examination a pupil's average marks were 63 per paper. If he had obtained 20 more marks for his Geography paper and 2 more marks for his History paper, his average per paper would have been 65. How many papers were there in the examination?

  • A. 8
  • B. 9
  • C. 10
  • D. 11

Explanation: The two corrections add 20 marks + 2 marks = 22 marks to the total. Since the average rises from 63 marks to 65 marks, the increase is 2…

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Correct answer: 11

226. The average salary of all the workers in a workshop is Rs. 8000. The average salary of 7 technicians is Rs. 12000 and the average salary of the rest is Rs. 6000. The total number of workers in the workshop is__________________?

  • A. 20
  • B. 21
  • C. 22
  • D. 23

Explanation: Let the total number of workers be n. The total salary is Rs. 8000n, while the two groups give Rs. 12000 x 7 + Rs. 6000 x (n - 7) = Rs.

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Correct answer: 21

227. The arithmetic mean of the scores of a group of students in a test was 52. The brightest 20% of them secured a mean score of 80 and the dullest 25% a mean score of 31. The mean score of remaining 55% is___________?

  • A. 45
  • B. 50
  • C. 51.4 approx.
  • D. 54.6 approx.

Explanation: Use a weighted average: the top 20% contribute 0.20 x 80 = 16 points and the bottom 25% contribute 0.25 x 31 = 7.75 points to the overall…

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Correct answer: 51.4 approx.

228. The average age of a husband, wife and their child 3 years ago was 27 years and that of wife and the child 5 years ago was 20 years. The present age of the husband is___________?

  • A. 35 years
  • B. 30 years
  • C. 40 years
  • D. None of these

Explanation: Three years ago, the combined age of the three people was 3 x 27 = 81 years, so their present combined age is 81 + 3 x 3 = 90 years.

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Correct answer: 40 years

229. A cricketer has a certain average for 10 innings. In the eleventh inning, he scored 108 runs, there by increasing his average by 6 runs. His new average is_____________?

  • A. 48 runs
  • B. 52 runs
  • C. 55 runs
  • D. 60 runs

Explanation: Let the original average be x runs, so the total for 10 innings was 10x runs.

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Correct answer: 48 runs

230. The captain of a cricket team of 11 members is 26 years old and the wicket keeper is 3 years older. If the ages of these two are excluded, the average age of the remaining players is one year less than the average age of the whole team. What is the average of the team?

  • A. 23 years
  • B. 24 years
  • C. 25 years
  • D. None of these

Explanation: Let the team's average age be x years, so the total age is 11x years. The captain and wicketkeeper together are 26 + 29 = 55 years, and…

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Correct answer: 23 years

231. 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

232. 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

233. 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

234. 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

235. 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

236. 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

237. 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

238. 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

239. 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

240. 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
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