Basic Maths Mcqs

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___________?

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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:
Let the required means score be x. Then,
20 * 80 + 25 * 31 + 55 * x = 52 * 100
= 1600 + 775 + 55x = 5200
= 55x = 2825
= x = 565/11 = 51.4.

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___________?

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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:
27×3+3×3=90 hsbnd,wife n child
20×2+5×2=50 wide n child
Hsbnd age= 90-50
= 40 yrs

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_____________?

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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 average for 10 innings be x. Then,
(10x + 108)/11 = x + 6
= 11x + 66 = 10x + 108
= x = 42.
New average = (x + 6) = 48 runs

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?

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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 average of the whole team be x years.
11x – (26 + 29) = 9(x – 1)
= 11x – 9x = 46
= 2x = 46 => x = 23
So, average age of the team is 23 years

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?

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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:
Manager’s monthly salary
= Rs. (1600 * 21 – 1500 * 20) = Rs. 3600

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____________?

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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. 5000
Explanation:
Let P, Q and R represent their respective monthly incomes. Then, we have:
P + Q = (5050 * 2) = 10100 — (i)
Q + R = (6250 * 2) = 12500 — (ii)
P + R = (5200 * 2) = 10400 — (iii)
Adding (i), (ii) and (iii), we get:
2(P + Q + R) = 33000 = P + Q + R = 16500 — (iv)
Subtracting (ii) from (iv), we get, P = 4000.
P’s monthly income = Rs. 4000

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____________?

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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:
Age of the 15th student=
[15 * 15 – (14 * 5 + 16 * 9)] = (225 – 214) = 11 years

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