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Average - Aptitude MCQ Questions and Solutions with Explanations

Average MCQ Questions and answers with easy and logical explanations.Arithmetic Ability provides you all type of quantitative and competitive aptitude mcq questions on Average with easy and logical explanations. Average MCQ is important for exams like Banking exams,IBPS,SCC,CAT,XAT,MAT etc. Page-3 section-4

Each section contains 100 MCQs on Average .
21
The average of six numbers is 32. If each of first three numbers is increased by 2 and each of the remaining three numbers is decreased by 4, then the new average is ?
Discuss
Answer & Solution
Answer: Option C
Solution:
According to the question,
First three numbers is increased by 2 = 3 × 2 = + 6
Remaining three numbers is decreased by 4 = (- 4 × 3) = - 12
Difference '- 6' effect on 6 numbers = $$\frac{- 6}{+ 6}$$   = - 1
∴ Previous average = 32
New average = 32 - 1 = 31
22
The average of all the odd integers between 2 an 22 is ?
Discuss
Answer & Solution
Answer: Option B
Solution:
Series → 3 + 5 + 7 . . . . . 21
Total numbers
$$\frac{{{\text{Last term }} - {\text{ First term}}}}{{{\text{Difference}}}}$$     + 1
= $$\frac{21 - 3}{2}$$ + 1
= $$\frac{18}{2}$$ + 1
= 10
Sum of series
$$\eqalign{ & = \frac{n}{2}\left[ {2a + \left( {n - 1} \right)d} \right] \cr & = \frac{{10}}{2}\left[ {2 \times 3 + \left( {10 - 1} \right) \times 2} \right] \cr & = 5\left[ {6 + 9 \times 2} \right] \cr & = 5 \times 24 \cr & = 120 \cr} $$
Average = $$\frac{120}{10}$$ = 12
23
The average weight of five persons sitting in a boat is 38 kg. The average weight of the boat and the persons sitting in the boat is 52 kg. What is the weight of the boat ?
Discuss
Answer & Solution
Answer: Option B
Solution:
Let the five persons be A, B, C, D, E
According to the question,
= $$\frac{A + B + C + D + E}{5}$$     = 38 kg
= A + B + C + D + E = 190 kg.....(i)
$$\frac{{5\,{\text{persons}} + {\text{Boat}}}}{6} = 52$$
5 persons + Boat = 312 kg.....(ii)
∴ Boat's weight = 312 - 190 = 122 kg
24
The average expenditure of a man for the first five months Rs. 1200 and for the next seven months is Rs. 1300. If he saves Rs. 2900 in that years, his monthly average income is -
Discuss
Answer & Solution
Answer: Option D
Solution:
Total expenditure
= 1200 × 5 + 1300 × 7
= Rs. 15100
Total savings = Rs. 2900
Total income = Rs. 18000
Average income = $$\frac{18000}{12}$$ = 1500
25
The average age of mother and her six children is 12 years, which is reduced by 5 years if the age of mother is excluded. The age of the mother (in years) is :
Discuss
Answer & Solution
Answer: Option C
Solution:
Mother + 6 children
= 12 × 7
= 84 years
6 children = 6 × 7 = 42 years
∴ Age of mother = 42 years
26
There are 50 students in a class. Their average weight is 45 kg. When one student leaves the class the average weight reduces by 100 g. What is the weight of the student who left the class ?
Discuss
Answer & Solution
Answer: Option C
Solution:
According to the question,
The average weight of 50 students was = 45 kg
When one student leaves the class the average reduced by 100 gm.
∴ Total weight reduction due to 49 students
= 49 × 100 = 4900 gm
= 4.9 kg
∴ The weight of student who left
= 45 + 4.9
= 49.9 kg
27
The mean of 20 items is 55. If two items 45 and 30 are removed, the new mean of the remaining items is :
Discuss
Answer & Solution
Answer: Option C
Solution:
According to the question,
Mean of 20 items is = 55
Sum of 20 items is
= 55 × 20 = 1100
Two items removed
= 45 + 30 = 75
Now, sum of 18 items
= 1100 - 75
= 1025
∴ Average = $$\frac{1025}{18}$$ = 56.9
28
The average weight of a group of 20 boys was calculated to be 89.4 kg and it was later discovered that one weight was misread as 78 kg instead of 87 kg. The correct average weight is -
Discuss
Answer & Solution
Answer: Option D
Solution:
According to the question,
Average weight of a 20 boys = 89.4 kg
Sum of a weight of 20 boys = 89.4 × 20 = 1788 kg
It was later discovered that one weight was misread as 78 kg instead of 87 kg.
∴ Difference = 87 - 78 = 9 kg
∴ Actual sum of a weight of 20 boys
= 1788 + 9
= 1797 kg.
Actual average = $$\frac{1797}{20}$$   = 89.85 kg
29
A batsman in his 12th innings makes a score of 63 runs and there by increases his average score by 2. What is his average after the 12th innings ?
Discuss
Answer & Solution
Answer: Option C
Solution:
Let the average score till his 11 innings = x
According to the question,
⇒ $$\frac{11x + 63}{12}$$   = x + 2
⇒ 11x + 63 = 12x + 24
⇒ x = 39
12th innings average = 39 + 2 = 41
30
Out of 10 teachers of a school, one teacher retires and in place of him a new teacher 25 years old joins. As a result of it average age of the teachers reduces by 3 years. Age of the retired teacher (in years) is -
Discuss
Answer & Solution
Answer: Option A
Solution:
Age of retired teacher
= 25 + (10 × 3)
= 25 + 30
= 55 years