UPSC Prelims 2026 · CSAT Paper 2 · Set DMathematicsQ 73 / 80

UPSC Prelims 2026 CSAT Paper 2 — Question 73

Question

A toy T jumps forward or backward. In each forward jump, it moves 5' forward whereas in each backward jump, it moves 2' backward. If in 31 jumps, T moves exactly 15' forward, then what is the difference of the number of forward and backward jumps?

(a)6
(b)7
(c)8
(d)9

UnlockIAS answer: (d)9

Solution

Let f forward and b backward jumps: f + b = 31 and 5f − 2b = 15. Solving gives f = 11, b = 20, so the difference is 20 − 11 = 9.

UnlockIAS expert key, prepared 24 May 2026 and cross-verified by re-deriving the answer — this is our key, not the official UPSC provisional key (awaited).

Section

Mathematics

Topic Reference

Numeracy — Linear equations

Official UPSC key still awaited

UPSC has announced (PIB Release 2262441, 18 May 2026) that the provisional answer key for CSE Prelims 2026 will be released “soon after Exam”. Until then, use the CSAT score calculator for your qualifying-status estimate, and join the per-question discussion below.

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Official Notification

PIB Release 2262441

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