Number System - Aptitude MCQ Questions and Solutions with Explanations

61

Arrangement of the fractions into ascending order : $$\frac{4}{3},$$ $$ - \frac{2}{9},$$ $$ - \frac{7}{8},$$ $$\frac{5}{{12}}$$

A) $$ - \frac{2}{9}, - \frac{7}{8},\frac{4}{3},\frac{5}{{12}}$$ B) $$ - \frac{7}{8}, - \frac{2}{9},\frac{5}{{12}}\frac{4}{3}$$ C) $$ - \frac{7}{8}, - \frac{2}{9},\frac{4}{3},\frac{5}{{12}}$$ D) $$ - \frac{2}{9}, - \frac{7}{8},\frac{5}{{12}}\frac{4}{3}$$

Discuss

Answer & Solution

Answer: Option B

Solution:

$$\frac{4}{3}, - \frac{2}{9}, - \frac{7}{8},\frac{5}{{12}}$$
$$\eqalign{ & \frac{4}{3} = 1.33, \cr & - \frac{2}{9} = - 0.22, \cr & - \frac{7}{8} = - 0.875, \cr & \frac{5}{{12}} = 0.416 \cr} $$
So, $$ - \frac{7}{8}, - \frac{2}{9},\frac{5}{{12}},\frac{4}{3}$$

62

If 1³ + 2³ + .....+ 10³ = 3025, then the value of 2³ + 4³ +.....+ 20³ is :

A) 7590 B) 5060 C) 24200 D) 12100

Discuss

Answer & Solution

Answer: Option C

Solution:

∵ 1³ + 2³ + .....+ 10³ = 3025
To find = 2³ + 4³ + 6³ +.....+ 20³ = ?
⇒ 2³ (1³ + 2³ + .....+ 10³)
⇒ 8 × 3025
⇒ 24200

63

There are 50 boxes and 50 persons. Person 1 keeps 1 marble in every box, person 2 keeps 2 marbles in every 2nd box, person 3 keeps 3 marbles in every third box. The process goes on till person 50 keeps 50 marbles in the 50th box. Find the total number of marbles kept in the 50th box.

A) 43 B) 78 C) 6 D) 93

Discuss

Answer & Solution

Answer: Option D

Solution:

Marbles in the 50th box will be kept by 1st, 2nd, 5th, 10th, 25th and 50th person is a factor of 50.
Number of marbles
=1 + 2 + 5 + 10 + 25 + 50
= 93

64

The difference between the greatest and the least four digit numbers that begins with 3 and ends with 5 is :

A) 900 B) 999 C) 909 D) 990

Discuss

Answer & Solution

Answer: Option D

Solution:

According to the question,
⇒ The least number = 3005
⇒ The greatest number = 3995
⇒ Difference will be = 3995 - 3005 = 990

65

If in a three digits number the last two digits places are interchanged a new number is formed which is greater than the original number by 45. What is the difference between the last two digits of that number ?

A) 9 B) 8 C) 6 D) 5

Discuss

Answer & Solution

Answer: Option D

Solution:

Three digit number = 100x + 10y + z
To make number after changing last two digit = 100x + 10z + y
Now,
100x + 10y + z = 100x + 10z + y - 45
9z - 9y = 45
z - y = 5

66

Which of the following is a perfect square ?

A) 3497497 B) 4587632 C) 1046529 D) 1034758

Discuss

Answer & Solution

Answer: Option C

Solution:

By checking last 3 digits
Then, last '3' digits of 1046529
529 is a square of 23
Hence, this is correct option

67

While solving a problem, by mistake, Anita squared a number and then subtracted 25 from it rather than first subtracting 25 from the number and then squaring it. But she got the right answer. What was the given number ?

A) 48 B) Cannot be determined C) 13 D) 38

Discuss

Answer & Solution

Answer: Option C

Solution:

Let the given number be x
According to the question,
x² - 25 = (x - 25)²
x² - 25 = x² + (25)² - 50x
x = 13

68

The decimal fraction $$2.3\overline {49} $$ is equal to :

A) $$\frac{{2326}}{{999}}$$ B) $$\frac{{2326}}{{990}}$$ C) $$\frac{{2347}}{{999}}$$ D) $$\frac{{2347}}{{990}}$$

Discuss

Answer & Solution

Answer: Option B

Solution:

$$2.3\overline {49} = \frac{{2349 - 23}}{{990}} = \frac{{2326}}{{990}}$$

69

A number x when divided by 289 leave 18 as the remainder. The same number when divided by 17 leaves y as a remainder. the value of y is :

A) 5 B) 2 C) 3 D) 1

Discuss

Answer & Solution

Answer: Option D

Solution:

$$\eqalign{ & \frac{{{\text{Remainder of number}}}}{{17}} = \frac{{18}}{{17}} \cr & \Rightarrow {\text{Remainder = 1}} \cr} $$

70

The digit at Hundred's place value of 17! is :

A) 1 B) 0 C) 2 D) 3

Discuss

Answer & Solution

Answer: Option B

Solution:

We know that after 5! we get one zero at the end of the number
And after 10! → two zeros
And after 15! → three zeros
We can say that in 17! we get minimum three zeros
The Hundred's place value of 17! = 0