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Number System - Aptitude MCQ Questions and Solutions with Explanations

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

Each section contains 100 MCQs on Number System .
31
The real number to be added to 13851 to get a number which is divisible by 87 is :
Discuss
Answer & Solution
Answer: Option D
Solution:
By hit and trial method
= 13851 + 69
= 13920
Which is divisible by 87
32
Among the following statements, the statement which is 'not correct' is :
Discuss
Answer & Solution
Answer: Option B
Solution:
Every real number is a rational number
33
Sum of three consecutive integers is 51. The middle one is -
Discuss
Answer & Solution
Answer: Option D
Solution:
Let numbers are a, a + 1, a + 2
Then,
a + a + 1 + a + 2 = 51
3a + 3 = 51
3a = 48
a = 16
Middle number :
= a + 1
= 16 + 1
= 17
34
The sum of 10 terms of the arithmetic series is 390. If the third term of the series is 19. Find the first term :
Discuss
Answer & Solution
Answer: Option A
Solution:
Sum of A.P. = $$\frac{n}{2}\left[ {2a + (n - 1)d} \right]$$
nth term = a + (n - 1)d
3rd term :
⇒ a + (3 - 1)d = 19
⇒ a + 2d = 19.....(i)
Sum of 10 term :
$$\eqalign{ & \Rightarrow \frac{{10}}{2}\left[ {2a + 9d} \right] = 390 \cr & \Rightarrow 2a + 9d = 78..... (ii) \cr & \Rightarrow a + 2d = 19 \cr} $$
From equation (i) and (ii)
a = 3
d = 8
35
If p = - 0.12, q = - 0.01 and r = - 0.015, then the correct relationship among the three is :
Discuss
Answer & Solution
Answer: Option A
Solution:
∵ p = - 0.12
q = - 0.01
r = - 0.015
If all values would be positive
0.12 > 0.015 > 0.01
p > r > q
But these are negative so their order will be
q > r > p
36
The sum of squares of three positive integers is 323. If the sum of squares of two numbers is twice the third, their product is :
Discuss
Answer & Solution
Answer: Option A
Solution:
Let the integers in a, b, c
a2 + b 2 + c2 = 323.....(i)
a2 + b2 + = 2c.....(ii)
Break the 323 in to their squares
a = 5
b = 3
c = 17
So, a2 + b2 + c2 = 323
and
a2 + b2 = 2c
252 + 32 = 2 × 17
34 = 34
So, Satisfied
a : b : c = 17 × 5 × 3 = 255
37
Each member of a club contributes as much rupees and as much paise as the number of members of the club. If the total contribution is Rs. 2525, then the number of members of the club is :
Discuss
Answer & Solution
Answer: Option D
Solution:
Let the total member be x
x members contribution is Rs. x
And each member also contributes x paise
So, total rupees is
x member Rs. x = Rs. x2
x member Rs. x paise = $$\frac{x.x}{100}$$
Total rupees is
$${x^2} + \frac{{{x^2}}}{{100}} = 2525$$
101x2 = 2525 × 100
101x2 = 101 × 25 × 100
x = 50
38
The sum of the cubes of two numbers in the ratio 3 : 4 is 5824. The sum of the numbers is :
Discuss
Answer & Solution
Answer: Option B
Solution:
Let numbers are = 3x, 4x
(3x)3 + (4x)3 = 5824
27x3 + 64x3 = 5824
91x3 = 5824
x3 = $$\frac{5824}{91}$$
x3 = 64
x = 4
So, numbers are
3x = 3 × 4 = 12
4x = 4 × 4 = 16
Sum = 12 + 16 = 28
39
The value of $$\left( {0.34\overline {67} + 0.13\overline {33} } \right)$$   is :
Discuss
Answer & Solution
Answer: Option B
Solution:
0.34676767 ..... + 0.13333333 .....
= 0.480101 .....
= $$0.48\overline {01} $$
40
Arrange the following fraction in decreasing order : $$\frac{3}{5},$$ $$\frac{7}{9}$$ $$,\frac{{11}}{{13}}$$
Discuss
Answer & Solution
Answer: Option C
Solution:
$$\frac{3}{5},\frac{7}{9},\frac{{11}}{{13}}$$
$$\eqalign{ & \frac{3}{5} = 0.60, \cr & \frac{7}{9} = 0.7, \cr & \frac{{11}}{{13}} = 0.8 \cr & \frac{{11}}{{13}}{\text{ > }}\frac{7}{9} > \frac{3}{5} \cr} $$