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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-7 section-2

Each section contains 100 MCQs on Average .
61
The average of six numbers is x and the average of three of these is y. If the average of the remaining three is z, then-
Discuss
Answer & Solution
Answer: Option B
Solution:
Clearly, we have :
$$\eqalign{ & \Rightarrow x = \left( {\frac{{3y + 3z}}{6}} \right) \cr & \Rightarrow 2x = y + z \cr} $$
62
The average of the first 100 positive integers is-
Discuss
Answer & Solution
Answer: Option B
Solution:
Required average
$$\eqalign{ & = \left( {\frac{{1 + 2 + 3 + .... + 100}}{{100}}} \right) \cr & = \frac{1}{{100}} \times \frac{{100 \times 101}}{2} \cr & = 50.5 \cr} $$
63
After replacing an old member by a new member, it was found that the average age of five members of a club is the same as it was 3 years ago. What is the difference between the ages of the replaced and the new member?
Discuss
Answer & Solution
Answer: Option D
Solution:
Age decreased = (5 × 3) years = 15 years
So, the required difference = 15 years
64
The average weight of 8 men is increased by 1.5 kg when one of the men, who weight 65 kg is replaced by a new man. The weight of the new man is-
Discuss
Answer & Solution
Answer: Option D
Solution:
Total weight increased = (8 × 1.5) kg = 12 kg
Weight of the new man = (65 + 12) kg = 77 kg
65
Total expenses of a boarding house are partly fixed and partly varying linearly with the number of boarders. The average expense per boarder is Rs. 700 when there are 25 boarders and Rs. 600 when there are 50 boarders. What is the average expense per boarder when there are 100 boarders?
Discuss
Answer & Solution
Answer: Option B
Solution:
Let the fixed cost be Rs. x and the variable cost be Rs. y per boarder.
Then,
x + 25y = 700 × 25
⇒ x + 25y = 17500.....(i)
x + 50y = 600 × 50
⇒ x + 50y = 30000.....(ii)
Subtracting (i) from (ii), we get:
25y = 12500
⇒ y = 500
Putting y = 500 in (i), we get:
x = 5000
∴ Total expenses of 100 boarders
= Rs. (5000 + 500 × 100)
= Rs. 55000
Hence, average expense
= Rs. $$\frac{55000}{100}$$
= Rs. 550
66
A shop of electronic goods is closed on Monday. The average daily sales for remaining six days of a week is Rs. 15,640 and the average sale of Tuesday to Saturday is Rs. 14,124. The sales on Sunday is -
Discuss
Answer & Solution
Answer: Option C
Solution:
Average sales per day for six days of the week = Rs. 15640
Total sales of six days of the week
= 15640 × 6
= Rs. 93840
Average sales to Tuesday to Saturday = Rs. 14124
Total sales from Tuesday to Saturday
= 14124 × 5
= Rs. 70620
∴ Sales on Sunday
= (Rs. 93840 - 70620)
= Rs. 23,220
67
The average expenditure of a man for the first five months is Rs. 1200 and for the next seven months is Rs. 1300. If he saves Rs. 2900 in that year, his monthly average income is-
Discuss
Answer & Solution
Answer: Option A
Solution:
Average expenditure of a man for the first five month = Rs. 1200
Average expenditure of a man for the next seven month = Rs. 1300
Total annual expenditure of man
= Rs. (5 × 1200 + 7 × 1300)
= Rs. (6000 + 9100)
= Rs. 15100
Man saves = Rs. 2900
His total annual income
= Rs. (15100 + 2900)
= Rs. 18000
∴ Average monthly income
= $$\frac{18000}{12}$$
= Rs. 1500
68
The average weight of 21 boys was recorded as 64 kg. If the weight of the teacher was added, the average increased by 1 kg. What was the teacher’s weight?
Discuss
Answer & Solution
Answer: Option A
Solution:
Average weights of 21 boys = 64 kg
Total weights of 21 boys
= 64 × 21
= 1344 kg
The weight of the teacher was added then average increase by 1 kg
⇒ Total weight of teacher and 21 boys
= 65 × 22
= 1430 kg
∴ Weight of teacher
= 1430 - 1344
= 86 kg
69
In a school with 600 students, the average age of the boys is 12 years and that of the girls is 11 years. If the average of the school is 11 years 9 months, then the average the number of girls in the school is :
Discuss
Answer & Solution
Answer: Option A
Solution:
Let the number of girls be x
Then, number of boys = (600 - x)
Then,
$$\left( {11\frac{3}{4} \times 600} \right)$$   = 11x + 12 (600 - x)
⇔ x = 7200 - 7050
⇔ x = 150
70
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-
Discuss
Answer & Solution
Answer: Option C
Solution:
Let the required mean score be x
Then,
$$\eqalign{ & 20 \times 80 + 25 \times 31 + 55 \times x = 52 \times 100 \cr & \Leftrightarrow 1600 + 775 + 55x = 5200 \cr & \Leftrightarrow 55x = 2825 \cr & \Leftrightarrow x = \frac{{2825}}{{55}} \approx 51.4 \cr} $$