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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-4 section-3

Each section contains 100 MCQs on Average .
31
The average price of 10 books is Rs. 12 while the average price of 8 of these books is Rs. 11.75. Of the remaining two books, if the price of one book is 60% more than the price of the other, what is the price of each of these two books?
Discuss
Answer & Solution
Answer: Option C
Solution:
Total price of the two books
= Rs. [(12 × 10) - (11.75 × 8)]
= Rs. (120 - 94)
= Rs. 26
Let the price of one book be Rs. x
Then, the price of other book
= Rs. (x + 60 % of x)
= Rs. $$\left( {x + \frac{3}{5}x} \right)$$
= Rs. $$\left( { \frac{8x}{5}} \right)$$
So, $${x + \frac{8x}{5}}$$   = 26
⇒ 13x = 130
⇒ x = 10
32
16 children are to be divided into two groups A and B of 10 and 6 children. The average percent marks obtained by the children of group A is 75 and the average percent marks of all the 16 children is 76. What is the average percent marks of children of group B ?
Discuss
Answer & Solution
Answer: Option B
Solution:
Required average
$$\eqalign{ & = \frac{{\left( {76 \times 16} \right) - \left( {75 \times 10} \right)}}{6} \cr & = \left( {\frac{{1216 - 750}}{6}} \right) \cr & = \frac{{466}}{6} \cr & = \frac{{233}}{3} \cr & = 77\frac{2}{3} \cr} $$
33
The average age of 30 students in a class is 15 years. If 6 students of this class have the average age of 16 years, then the average age of the remaining 24 students would be-
Discuss
Answer & Solution
Answer: Option D
Solution:
Sum of the ages of 24 students
= (15 × 30) - (16 × 6)
= 450 - 96
= 354
∴ Required average
= $$\left( {\frac{{354}}{{24}}} \right)$$
= $$14\frac{3}{4}$$ yrs
= 14 yrs 9 mths
34
Of the four numbers, the first is twice the second, the second is one-third of the third and the third is 5 times the fourth. The average of the numbers is 24.75. The largest of these numbers is-
Discuss
Answer & Solution
Answer: Option D
Solution:
Let the fourth number be x
Then, third number = 5x
Second number = $$\frac{5x}{3}$$ and
First number = $$\frac{10x}{3}$$
x + 5x + $$\frac{5x}{3}$$  + $$\frac{10x}{3}$$   = (24.75 × 4)
⇒ 11x = 99
⇒ x = 9
So, the numbers are 9, 45, 15 and 30
∴ Largest number = 45
35
A car owner buys petrol at Rs. 17, Rs. 19 and Rs. 20 per litre for three consecutive years. Compute the average cost per litre, if he spends Rs 6460 per year.
Discuss
Answer & Solution
Answer: Option B
Solution:
Total quantity of petrol consumed in 3 years
= $$\left( {\frac{{6460}}{{17}} + \frac{{6460}}{{19}} + \frac{{6460}}{{20}}} \right)$$   litres
= (380 + 340 + 323) litres
= 1043 litres
Total amount spent
= Rs. (3 × 6460)
= Rs. 19380
∴ Average cost
= Rs. $$\left( {\frac{{19380}}{{1043}}} \right)$$
= Rs. 18.58
36
The average of five consecutive numbers is x. If the next two numbers are included, how shall the average vary?
Discuss
Answer & Solution
Answer: Option A
Solution:
Let the five consecutive numbers be z, z + 1, z + 3 and z + 4
Then,
$$ \Rightarrow \frac{{z + \left( {z + 1} \right) + \left( {z + 2} \right) + \left( {z + 3} \right) + \left( {z + 4} \right)}}{5} = x$$
$$\eqalign{ & \Rightarrow 5z + 10 = 5x \cr & \Rightarrow z = \frac{{5x - 10}}{5} \cr & \Rightarrow z = x - 2 \cr} $$
So, the numbers are x - 2, x - 1, x, x + 1, x + 2
∴ Required mean
$$ = \frac{{\left( {x - 2} \right) + \left( {x - 1} \right) + x + \left( {x + 1} \right) + \left( {x + 2} \right) + \left( {x + 3} \right) + \left( {x + 4} \right)}}{7}$$
$$\eqalign{ & = \frac{{7x + 7}}{7} \cr & = x + 1 \cr} $$
37
In a certain factory there are five workers A, B, C, D and E. A can complete a work in 4 minutes, B in 5 minutes, C in 6 minutes, D in 10 minutes and E in 12 minutes. The average number of units of work completed per worker per minute will be-
Discuss
Answer & Solution
Answer: Option A
Solution:
Number of units of work completed by the five workers in 1 minute:
$$\eqalign{ & A \to \frac{1}{4}, \cr & B \to \frac{1}{5}, \cr & C \to \frac{1}{6}, \cr & D \to \frac{1}{{10}}, \cr & E \to \frac{1}{{12}} \cr} $$
∴ Required average
$$\eqalign{ & = \frac{{\left( {\frac{1}{4} + \frac{1}{5} + \frac{1}{6} + \frac{1}{{10}} + \frac{1}{{12}}} \right)}}{5} \cr & = \left( {\frac{4}{5} \times \frac{1}{5}} \right) \cr & = \frac{4}{{25}} \cr & = 0.16 \cr} $$
38
The average expenditure of a man for the first five months of a year is Rs. 5000 and for the next seven months it is Rs. 5400. He saves Rs. 2300 during the year. His average monthly income is-
Discuss
Answer & Solution
Answer: Option A
Solution:
Total yearly income
= Rs. (5000 × 5 + 5400 × 7 + 2300)
= Rs. (25000 + 37800 + 2300)
= Rs. 65100
∴ Average monthly income
= Rs. $$\left( {\frac{{65100}}{{12}}} \right)$$
= Rs. 5425
39
The average weight of 16 boys in a class is 50.25 kgs and that of the remaining 8 boys is 45.15 kgs. Find the average weight of all the boys in the class.
Discuss
Answer & Solution
Answer: Option C
Solution:
Required mean
$$\eqalign{ & = \left( {\frac{{50.25 \times 16 + 45.15 \times 8}}{{16 + 8}}} \right) \cr & = \left( {\frac{{804 + 361.20}}{{24}}} \right) \cr & = \frac{{1165.20}}{{24}} \cr & = 48.55 \cr} $$
40
A library has an average of 510 visitors on Sundays and 240 on other days. The average number of visitors per day in a month of 30 days beginning with a Sunday is-
Discuss
Answer & Solution
Answer: Option D
Solution:
Since the month begins with a Sunday, so there will be five Sundays in the month.
∴ Required average
$$\eqalign{ & = \left( {\frac{{510 \times 5 + 240 \times 25}}{{30}}} \right) \cr & = \frac{{8550}}{{30}} \cr & = 285 \cr} $$