Average MCQs with Answers and Explanations for Competitive Exams

Question #41

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The average age of 6 children is 10 years. If the age of one child is 8, find the average age of the remaining 5.

A. 10.4

B. 10

C. 11

D. 9.6

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Correct Answer: Option A

Explanation:
Sum=6×10=60. Remaining sum=60-8=52. Avg=52/5=10.4.

This question belongs to: Maths Average

Question #42

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The average of 4 numbers is 25. If the numbers are in the ratio 2:3:4:5, find the smallest number.

A. 14.29

B. 13.5

C. 14

D. 15

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Correct Answer: Option A

Explanation:
Sum=4×25=100. Ratio sum=14. Smallest = (2/14)×100 =14.285...≈14.29.

This question belongs to: Maths Average

Question #43

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The average of 6 numbers is 12. If one number is 20, find the average of the rest.

A. 10

B. 10.4

C. 11

D. 9.6

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Correct Answer: Option B

Explanation:
Sum=6×12=72. Rest sum=72-20=52. Average=52/5=10.4.

This question belongs to: Maths Average

Question #44

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Find the average of all numbers divisible by 5 between 10 and 30 (inclusive).

A. 22.5

B. 20

C. 20.5

D. 17.5

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Correct Answer: Option B

Explanation:
Numbers: 10,15,20,25,30 sum=100, count=5, avg=20.

This question belongs to: Maths Average

Question #45

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The average of 8 numbers is 22. If each number is decreased by 2, what is the new average?

A. 22

B. 20

C. 24

D. 18

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Correct Answer: Option B

Explanation:
New average =22-2=20.

This question belongs to: Maths Average

Question #46

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The average marks of 30 students is 60. If the marks of 10 students are averaged 50, what is the average of the remaining 20 students?

A. 62.5

B. 60

C. 65

D. 67.5

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Correct Answer: Option C

Explanation:
Total sum =30×60=1800. Sum of 10 =10×50=500. Sum of remaining 20 =1800-500=1300. Average =1300/20=65.

This question belongs to: Maths Average

Question #47

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The average of 5 numbers is 18. If one number is 25 and another is 15, find the average of the remaining 3 numbers.

A. 18

B. 17

C. 16

D. 16.67

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Correct Answer: Option D

Explanation:
Sum=5×18=90. Sum of two=25+15=40. Sum of three=50. Average=50/3=16.67.

This question belongs to: Maths Average

Question #48

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What is the average of the first 6 multiples of 2?

A. 6

B. 7

C. 9

D. 8

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Correct Answer: Option B

Explanation:
Multiples:2,4,6,8,10,12 sum=42, count=6, avg=7.

This question belongs to: Maths Average

Question #49

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The average of 7 numbers is 28. If one number is 40, find the average of the remaining 6.

A. 25

B. 27

C. 26

D. 24

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Correct Answer: Option C

Explanation:
Sum=7×28=196. Remaining sum=196-40=156. Average=156/6=26.

This question belongs to: Maths Average

Question #50

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The average height of 4 boys is 1.5 m. If a girl of height 1.6 m joins, what is the new average?

A. 1.53 m

B. 1.52 m

C. 1.5 m

D. 1.55 m

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Correct Answer: Option B

Explanation:
Sum of 4 =4×1.5=6.0. Sum of 5=6.0+1.6=7.6. Average=7.6/5=1.52.

This question belongs to: Maths Average

Question #51

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The average of 10 numbers is 15. If each number is increased by 10, what is the new average?

A. 30

B. 15

C. 20

D. 25

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Correct Answer: Option D

Explanation:
New average =15+10=25.

This question belongs to: Maths Average

Question #52

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The average of 3 numbers is 12. If the first is 10 and the second is 15, find the third.

A. 11

B. 9

C. 12

D. 13

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Correct Answer: Option A

Explanation:
Sum=3×12=36. Third=36-10-15=11.

This question belongs to: Maths Average

Question #53

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The average of 5 numbers is 26. If one number is 30, find the average of the rest.

A. 26

B. 24.5

C. 25.5

D. 25

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Correct Answer: Option D

Explanation:
Sum=5×26=130. Rest sum=130-30=100. Avg=100/4=25.

This question belongs to: Maths Average

Question #54

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The average of 5 numbers is 20. If each number is divided by 2, what is the new average?

A. 15

B. 10

C. 20

D. 5

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Correct Answer: Option B

Explanation:
New average =20/2=10.

This question belongs to: Maths Average

Question #55

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The average of 4 numbers is 15. If one number is 0, what is the average of the other three?

A. 22.5

B. 20

C. 18

D. 15

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Correct Answer: Option B

Explanation:
Sum=4×15=60. Other sum=60-0=60. Avg=60/3=20.

This question belongs to: Maths Average

Question #56

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Find the average of the first 5 composite numbers.

A. 7.4

B. 7.6

C. 8

D. 6.8

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Correct Answer: Option A

Explanation:
First 5 composites: 4,6,8,9,10 sum=37, avg=37/5=7.4.

This question belongs to: Maths Average

Question #57

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The average of 9 numbers is 30. If each number is increased by 2, what is the new average?

A. 34

B. 32

C. 28

D. 30

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Correct Answer: Option B

Explanation:
New average =30+2=32.

This question belongs to: Maths Average

Question #58

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The average of 6 numbers is 24. If one number is 36, find the average of the rest.

A. 22.8

B. 22

C. 21.6

D. 20.4

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Correct Answer: Option C

Explanation:
Sum=6×24=144. Rest sum=144-36=108. Avg=108/5=21.6.

This question belongs to: Maths Average

Question #59

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The average of 3 numbers is 15. If each number is multiplied by 4, what is the new average?

A. 30

B. 60

C. 45

D. 75

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Correct Answer: Option B

Explanation:
New average =15×4=60.

This question belongs to: Maths Average

Question #60

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What is the average of the first 9 odd numbers?

A. 9.5

B. 8.5

C. 10

D. 9

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Correct Answer: Option D

Explanation:
Sum of first n odd numbers = n^2 =9^2=81. Average=81/9=9.

This question belongs to: Maths Average

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