Averages – Aptitude Questions and Answers Online Test

Averages - Aptitude Questions and Answers



Averages aptitude questions and answers section with explanation. Practice online test for various interview, competitive and entrance exams.

1. Five years ago the average of the ages of A and B was 40 years and now the average of the ages of B and C is 48 years. What will be the age of the B ten years hence?

A.55 years                   B.56 years           C.58 years        D.Data inadequate           E.None of these

Answer: D

Explanation:

Let the present ages of A, B and C be a, b and c respectively.
Given, [(a – 5) + (b – 5)] / 2 = 40 => a + b = 90 — (1)
(b + c)/2 = 48 => b + c = 96 — (2)
From (1) and (2), we cannot find b.

2. The total marks obtained by a student in Mathematics and Physics is 60 and his score in Chemistry is 20 marks more than that in Physics. Find the average marks scored in Mathamatics and Chemistry together.

A.40                    B.30    C.25      D.Data inadequate E.None of these.

Answer: A

Explanation:

Let the marks obtained by the student in Mathematics, Physics and Chemistry be M, P and C respectively. 
Given , M + C = 60 and C – P = 20 M + C / 2 = [(M + P) + (C – P)] / 2 = (60 + 20) / 2 = 40.

3. The average weight of a group of persons increased from 48 kg to 51 kg, when two persons weighing 78 kg and 93 kg join the group. Find the initial number of members in the group?

A.21                 B.22            C.23     D.24          E.None of these

Answer: C

Explanation:

Let the initial number of members in the group be n.
Initial total weight of all the members in the group = n(48)
From the data,
48n + 78 + 93 = 51(n + 2) => 51n – 48n = 69 => n = 23
Therefore there were 23 members in the group initially.

4. A trader purchased two colour televisions for a total of Rs. 35000. He sold one colour television at 30% profit and the other 40% profit. Find the difference in the cost prices of the two televisions if he made an overall profit of 32%?

A.Rs. 21000 B.Rs. 17500 C.Rs. 19000 D.Rs. 24500 E.None of these

Answer: A

Explanation:

Let the cost prices of the colour television sold at 30% profit and 40% profit be Rs. x and Rs. (35000 – x) respectively.
Total selling price of televisions = x + 30/100 x + (35000 – x) + 40/100 (35000 – x)
=> 130/100 x + 140/100 (35000 – x) = 35000 + 32/100 (35000)
x = 28000
35000 – x = 7000
Difference in the cost prices of televisions = Rs. 21000

5. Rs. 6000 is lent out in two parts. One part is lent at 7% p.a simple interest and the other is lent at 10% p.a simple interest. The total interest at the end of one year was Rs. 450. Find the ratio of the amounts lent at the lower rate and higher rate of interest?

A.5 : 1 B.4 : 1 C.3 : 2 D.2 : 1 E.None of these

Answer: A

Explanation:

Let the amount lent at 7% be Rs. x
Amount lent at 10% is Rs. (6000 – x)
Total interest for one year on the two sums lent 
= 7/100 x + 10/100 (6000 – x) = 600 – 3x/100
=> 600 – 3/100 x = 450 => x = 5000
Amount lent at 10% = 1000
Required ratio = 5000 : 1000 = 5 : 1

6. A total of 3000 chocolates were distributed among 120 boys and girls such that each boy received 2 chocolates and each girl received 3 chocolates. Find the respective number of boys and girls?

A.70, 50           B.60, 60      C.50, 70    D.40, 80       E.None of these

Answer: B

Explanation:

Let the number of boys be x.
Number of girls is 120 – x.
Total number of chocolates received by boys and girls = 2x + 3(120 – x) = 300 
=> 360 – x = 300 => x = 60. 
So, the number of boys or girls is 60.

7. A student scored an average of 80 marks in 3 subjects: Physics, Chemistry and Mathematics. If the average marks in Physics and Mathematics is 90 and that in Physics and Chemistry is 70, what are the marks in Physics?

A.60               B.64         C.72             D.80         E.None of these

Answer: D

Explanation:

Given M + P + C = 80 * 3 = 240 — (1)
M + P = 90 * 2 = 180 — (2)
P + C = 70 * 2 = 140 — (3)
Where M, P and C are marks obtained by the student in Mathematics, Physics and Chemistry.
P = (2) + (3) – (1) = 180 + 140 – 240 = 80

8. The average mark of the students of a class in a particular exam is 80. If 5 students whose average mark in that exam is 40 are excluded, the average mark of the remaining will be 90. Find the number of students who wrote the exam.

A.20            B.15 C.25             D.35             E.None of these.

Answer: C

Explanation:

Let the number of students who wrote the exam be x.
Total marks of  students = 80 x.
Total marks of (x – 5) students = 90(x – 5)
80x – (5 * 40) = 90(x – 5)
250 = 10x  => x = 25

9. In an exam, Amar scored 64 percent, Bhavan scored 36 percent and Chetan 44 percent. The maximum score awarded in the exam is 800. Find the average mark scored by all the three boys?

A.384           B.364        C.324         D.404 E.None of these

Answer: A

Explanation:

Average mark scored by all the three boys = 
[64/100 (800) + 36/100 (800) + 44/100 (800)] / 3 = 384

10. The average height of 50 pupils in a class is 150 cm. Five of them whose height is 146 cm, leave the class and five others whose average height is 156 cm, join. The new average height of the pupils of the class (in cm) is __________ .

A.149           B.151        C.152    D.153 E.None of these.

Answer: B

Explanation:

Total height = 150 * 50 = 7500 cm.
New average = [7500 – 5 * 146 + 5 * 156 ] /  50 = 151 cm.


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