NDA & NA Exam (I)- 2026 - Mathematics Defence Question Paper

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NDA & NA Exam (I)- 2026 - Mathematics

NDA & NA Exam (I)- 2026 - Mathematics Defence Questions

1.
Let p, q and r be three unequal numbers such that p, q and r are in AP. If \( (q - p) \), \( (r - q) \) and p are in GP, then \( (p + q) : (q + r) : (r + p) \) equals
A.
1 : 2 : 3
B.
3 : 4 : 5
C.
3 : 5 : 4
D.
1 : 3 : 2
ANSWER :
C. 3 : 5 : 4
2.
If p, \( g_{1} \), \( g_{2} \) and q are in GP and m is the arithmetic mean of p and q, then \( \frac{g_{1}^{2}}{g_{2}} + \frac{g_{2}^{2}}{g_{1}} \) is equal to
A.
m
B.
2m
C.
1
D.
\( \frac{1}{2} \)
ANSWER :
B. 2m
3.
Consider the following inequalities:
I. \( 1 + 4i > 3 + 2i \)
II. \( 2 + 3i < 3 + 4i \)
III. \( 4 + 3i > 3 + 4i \)
where \( i = \sqrt{-1} \)
How many of the above are valid?
A.
None
B.
One
C.
Two
D.
All the three
ANSWER :
A. None
4.
Let \( Z_{1} \) and \( Z_{2} \) be complex numbers such that \( \frac{3Z_{1}}{4Z_{2}} \) is purely imaginary. What is \( \left|\frac{Z_{1} + Z_{2}}{Z_{1} - Z_{2}}\right| \) equal to?
A.
2
B.
\( \frac{3}{5} \)
C.
\( \frac{5}{4} \)
D.
1
ANSWER :
D. 1
5.
If \( \alpha \), \( \beta \), \( \gamma \) are cube roots of −8, then what is \( \frac{\alpha^{2}p^{2} + \beta^{2}q^{2} + \gamma^{2}r^{2}}{\beta^{2}p^{2} + \gamma^{2}q^{2} + \alpha^{2}r^{2}} \) equal to?
A.
\( \frac{\gamma}{\alpha} \)
B.
\( \frac{\gamma}{\beta} \)
C.
\( \frac{2\gamma}{\alpha} \)
D.
\( \frac{2\gamma}{\beta} \)
ANSWER :
B. \( \frac{\gamma}{\beta} \)
6.
The sum of the first n terms of an AP is \( 3n^{2} + 5n \). If the mth term of the AP is 68, then what is the value of m?
A.
9
B.
10
C.
11
D.
12
ANSWER :
C. 11
7.
A set S contains \( (2n + 1) \) elements. If the number of subsets of S which contain at most n elements is 1024, then what is the value of n?
A.
10
B.
8
C.
6
D.
5
ANSWER :
D. 5
8.
What is the maximum number of points of intersection of 5 circles?
A.
10
B.
15
C.
20
D.
25
ANSWER :
C. 20
9.
What is the greatest value of r satisfying the inequality \( {}^{15}C_{r} > 2 \times {}^{15}C_{r-1} \)?
A.
2
B.
3
C.
4
D.
5
ANSWER :
D. 5
10.
If \( n = {}^{m}C_{2} \), then what is \( {}^{n}C_{2} \) equal to?
A.
\( {}^{m+1}C_{4} \)
B.
\( 2 \times {}^{m+1}C_{4} \)
C.
\( 3 \times {}^{m+1}C_{4} \)
D.
\( {}^{m+2}C_{4} \)
ANSWER :
C. \( 3 \times {}^{m+1}C_{4} \)