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NDA (II) 2025 · Mathematics

A full Mathematics paper in the UPSC NDA pattern. 120 questions in 150 minutes, with a third of the marks deducted for every wrong answer.

120questions

300marks

+2.5 / −0.83per question

36/64/20easy / medium / hard

Sections and topics

One 120-question Mathematics paper covering algebra, trigonometry, calculus, geometry, vectors, statistics and probability.

Sets · medium

n(A)=20

n(B)=15

and

n(A\cap B)=8

, then the number of elements in the symmetric difference

A\triangle B

Show answer and solution

Answer: B

n(A\cup B)=20+15-8=27

. The symmetric difference removes the common part:

n(A\triangle B)=27-8=19

, equivalently

(20-8)+(15-8)=12+7=19

. The value

27

is the union, not the symmetric difference.