NDA & NA Exam (II)- 2025 - Mathematics Defence Question Paper

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NDA & NA Exam (II)- 2025 - Mathematics

NDA & NA Exam (II)- 2025 - Mathematics Defence Questions

41.
What is the sum of the binary numbers \( (101101101)_{2} \) and \( (100011)_{2} \)?
A.
\( (110010000)_{2} \)
B.
\( (110001000)_{2} \)
C.
\( (110000100)_{2} \)
D.
\( (100100000)_{2} \)
ANSWER :
A. \( (110010000)_{2} \)
42.
Set X contains \( 3n \) elements and set Y contains \( 2n \) elements, and they have \( n \) elements in common. How many elements does \( (X - Y) \times (Y - X) \) have?
A.
\( 5n^{2} \)
B.
\( 4n^{2} \)
C.
\( 3n^{2} \)
D.
\( 2n^{2} \)
ANSWER :
D. \( 2n^{2} \)
43.
Let \( A = \{-3, -2, -1, 0, 1, 2, 3\} \) and \( B = \{0, 1, 4, 9\} \). How many elements does the subset of \( A \times B \) corresponding to the relation \( R = \{(x, y) : |x| < y\} \) have, where \( x \in A \) and \( y \in B \)?
A.
9
B.
12
C.
15
D.
16
ANSWER :
C. 15
44.
Consider the following statements:
Statement-I: If \( X \) is an \( n \times n \) matrix, then \( \det(mX) = m^{n} \det(X) \), where \( m \) is a scalar.
Statement-II: If \( Y \) is a matrix obtained from \( X \) by multiplying any row or column by a scalar \( m \), then \( \det(Y) = m \det(X) \).
Which one of the following is correct in respect of the above statements?
A.
Both Statement-I and Statement-II are correct and Statement-II explains Statement-I
B.
Both Statement-I and Statement-II are correct but Statement-II does not explain Statement-I
C.
Statement-I is correct but Statement-II is not correct
D.
Statement-I is not correct but Statement-II is correct
ANSWER :
A. Both Statement-I and Statement-II are correct and Statement-II explains Statement-I
45.
Consider the following statements about the matrix \( M = \begin{bmatrix} 71 & 23 & 48 \\ 57 & 28 & 29 \\ 65 & 17 & 48 \end{bmatrix} \):
Statement-I: The inverse of \( M \) does not exist.
Statement-II: \( M \) is non-singular.
Which one of the following is correct in respect of the above statements?
A.
Both Statement-I and Statement-II are correct and Statement-II explains Statement-I
B.
Both Statement-I and Statement-II are correct but Statement-II does not explain Statement-I
C.
Statement-I is correct but Statement-II is not correct
D.
Statement-I is not correct but Statement-II is correct
ANSWER :
C. Statement-I is correct but Statement-II is not correct
46.
What is \( \cot^{-1} 9 + \mathrm{cosec}^{-1}\left(\frac{\sqrt{41}}{4}\right) \) equal to?
A.
\( \frac{\pi}{4} \)
B.
\( \frac{\pi}{3} \)
C.
\( \frac{\pi}{2} \)
D.
\( \pi \)
ANSWER :
A. \( \frac{\pi}{4} \)
47.
How many values of \( \theta \), where \( -\pi < \theta < \pi \), satisfy both the equations \( \cot \theta = -\sqrt{3} \) and \( \mathrm{cosec} \theta = -2 \) simultaneously?
A.
4
B.
2
C.
1
D.
None
ANSWER :
C. 1
48.
If \( x + \frac{1}{x} = 2\cos \theta \), then what is \( x^{3} + \frac{1}{x^{3}} \) equal to?
A.
\( \cos^{3} \theta \)
B.
\( \cos 3\theta \)
C.
\( 2\cos 3\theta \)
D.
\( 3\cos 3\theta \)
ANSWER :
C. \( 2\cos 3\theta \)
49.
If \( 0 < x \leq \pi \), then what is the number of values of \( x \) satisfying the equation \( \tan x + \sec x = 2\cos x \)?
A.
0
B.
1
C.
2
D.
3
ANSWER :
C. 2
50.
What is the value of
\( \tan\left[\frac{1}{2}\sec^{-1}\left(\frac{2}{\sqrt{3}}\right)\right] \)?
A.
\( 2 - \sqrt{3} \)
B.
\( 2 + \sqrt{3} \)
C.
\( \sqrt{3} - 1 \)
D.
\( \sqrt{3} + 1 \)
ANSWER :
A. \( 2 - \sqrt{3} \)