Arithmetic Mcqs

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___________?

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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:
Let there be x pupils in the class.
Total increase in marks = (x * 1/2) = x/2
x/2 = (83 – 63) => x/2 = 20 => x = 40

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___________?

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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:
Correct sum = (36 * 50 + 48 – 23) = 1825.
Correct mean = 1825/50 = 36.5

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___________?

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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:
A.M. of 75 numbers = 35
Sum of 75 numbers = 75 * 35 = 2625
Total increase = 75 * 5 = 375
Increased sum = 2625 + 375 = 3000
Increased average = 3000/75 = 40

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?

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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:
Required run rate
= [282 – (3.2 * 10)]/40 = 250/40 = 6.25

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?

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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:
Average after 11 innings = 36
Required number of runs
= (36 * 11) – (32 * 10) = 396 – 320 = 76

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?

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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:
Sum of the ages of 14 students
= (16 * 35) – (14 * 21) = 560 – 294 = 266
Required average = (266/14) = 19 years

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___________?

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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. 285
Explanation:
Since the month begins with a Sunday, so there will be five Sundays in the month.
Required average = [(510 * 5) + (240 * 25)]/30 = 8550/30 = 285

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?

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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:
Required Average = [(67 * 2) + (35 * 2 ) + (6 * 3)]/(2 + 2 + 3)
= (134 + 70 + 18)/7 = 31 5/7 years.

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

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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
Let the numbers x, x + 2, x + 4, x + 6 and x + 8
Then, [x + (x + 2) + (x + 4) + (x + 6) + (x + 8)]5 = 61
or 5x + 20 = 305 => x = 57
So, required difference = (57 + 8) – 57 = 8