Mathematics Mcqs

The average of 35 numbers is 25. If each number is multiplied by 5, find the new average?

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The average of 35 numbers is 25. If each number is multiplied by 5, find the new average?

A. 125
B. 134
C. 170
D. 98
Sum of the 35 numbers = 35 * 25 = 875
If each number is multiplied by 5, the sum also gets multiplied by 5 and the average also gets multiplied by 5.
Thus, the new average = 25 * 5 = 125

The average salary of a person for the months of January, February, March and April is Rs.8000 and that for the months February, March, April and May is Rs.8500. If his salary for the month of May is Rs.6500, find his salary for the month of January?

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The average salary of a person for the months of January, February, March and April is Rs.8000 and that for the months February, March, April and May is Rs.8500. If his salary for the month of May is Rs.6500, find his salary for the month of January?

A. 3000
B. 2500
C. 4500
D. 5000
Sum of the salaries of the person for the months of January, February, March and April = 4 * 8000 = 32000 —-(1)
Sum of the salaries of the person for the months of February, March, April and May = 4 * 8500 = 34000 —-(2)
(2)-(1) i.e. May – Jan = 2000
Salary of May is Rs.6500
Salary of January = Rs.4500

The average marks of a class of 30 students is 40 and that of another class of 50 students is 60. Find the average marks of all the students?

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The average marks of a class of 30 students is 40 and that of another class of 50 students is 60. Find the average marks of all the students?

A. 50
B. 47.5
C. 59
D. 52.5
Sum of the marks for the class of 30 students = 30 * 40 = 1200
Sum of the marks for the class of 50 students = 50 * 60 = 3000
Sum of the marks for the class of 80 students =
1200 + 3000 = 4200
Average marks of all the students = 4200/80 = 52.5

A batsman makes a score of 64 runs in the 16th innings and thus increased his average by 3. Find his average after the 16th inning?

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A batsman makes a score of 64 runs in the 16th innings and thus increased his average by 3. Find his average after the 16th inning?

A. 17
B. 29
C. 18
D. 19
Let the average after the 16th inning be P.
So, the average after the 15th inning will be (P-3) Hence, 15(P-30) + 64 = 16P => P = 19

The average of 13 numbers is 60. Average of the first 7 of them is 57 and that of the last 7 is 61. Find the 8th number?

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The average of 13 numbers is 60. Average of the first 7 of them is 57 and that of the last 7 is 61. Find the 8th number?

A. 46
B. 32
C. 68
D. 51
Explanation:
Sum of all the 13 numbers = 13 * 60 = 780
Sum of the first 7 of them = 7 * 57 = 399
Sum of the last 7 of them = 7 * 61 = 427
So, the 8th number = 427 + 399 – 780 = 46

The average of 11 results is 50, if the average of first six results is 49 and that of the last six is 52. Find the sixth result?

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The average of 11 results is 50, if the average of first six results is 49 and that of the last six is 52. Find the sixth result?

A. 46
B. 56
C. 34
D. 57
Explanation:
1 to 11 = 11 * 50 = 550
1 to 6 = 6 * 49 = 294
6 to 11 = 6 * 52 = 312
6th = 294 + 312 – 550 = 56

Three years ago the average age of a family of six members was 19 years. A boy have been born, the average age of the family is the same today. What is the age of the boy?

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Three years ago the average age of a family of six members was 19 years. A boy have been born, the average age of the family is the same today. What is the age of the boy?

A. 1 year
B. 1.5 years
C. 2 years
D. 2.5 years
6 * 22 = 132
7 * 19 = 133
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The average salary per head of the entire staff of an office including the officers and clerks is Rs.90. The average salary of officers is Rs.600 and that of the clerks is Rs.84. If the number of officers is 2, find the number of officers in the office?

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The average salary per head of the entire staff of an office including the officers and clerks is Rs.90. The average salary of officers is Rs.600 and that of the clerks is Rs.84. If the number of officers is 2, find the number of officers in the office?

A. 1540
B. 960
C. 840
D. 1020